Magnet recycling to create Nd—Fe—B magnets with improved or restored magnetic performance

ABSTRACT

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for recycling magnetic material to restore or improve the magnetic performance. One of the methods includes demagnetizing magnetic material from a waste magnet assembly by cyclic heating and cooling of the magnetic material, fragmenting adhesives attached to the magnetic material, cracking coating layers of the magnetic material, and subjecting the magnetic material to at least one of: a) a mechanical treatment or b) a chemical treatment, to remove the coating layers and prepare the magnetic material without impurities, fragmenting the demagnetized magnetic material to form a powder, and mixing the powder with a rare earth material R and an elemental additive A to produce a homogeneous powder, wherein the rare earth material R comprises at least one of: Nd or Pr, and the elemental additive A comprises at least one of: Nd, Pr, Dy, Co, Cu, and Fe.

BACKGROUND

The present disclosure relates to the manufacture of aNeodymium-Iron-Boron (Nd—Fe—B) sintered magnet from waste magneticmaterial.

The global market for Rare Earth Permanent Magnets (REPM) is growingtogether with the range of REPM applications. REPM's exhibit highmagnetic performance characteristics, and are used in the development ofhigh-tech, high-efficiency applications in many industries includingelectronics, energy, transportation, aerospace, defense, medicaldevices, and information and communication technology.

For example, applications using the Nd—Fe—B permanent magnets include:starter motors, anti-lock braking systems (ABS), fuel-pumps, fans,loudspeakers, microphones, telephone ringers, switches, relays,hard-disk drives (HDD), stepper motors, servo-motors, magnetic resonanceimaging (MRI), windmill generators, robotics, sensors, magneticseparators, guidance systems, satellites, cruise missiles, and so on.

The Nd—Fe—B type sintered magnet has a very fine tuned elementalcomposition, which includes, besides Nd, elements like Dy, Tb, Ga, Co,Cu, Al and other minor transitional metal elemental additions.

SUMMARY

In general, one innovative aspect of the subject matter described inthis specification can be embodied in methods that include the actionsof demagnetizing magnetic material from a waste magnet assembly bycyclic heating and cooling of the magnetic material, fragmentingadhesives attached to the magnetic material, cracking coating layers ofthe magnetic material, and subjecting the magnetic material to at leastone of: a) a mechanical treatment or b) a chemical treatment, to removethe coating layers and prepare the magnetic material without impurities,fragmenting the demagnetized magnetic material to form a powder, andmixing the powder with a) a rare earth material R and b) an elementaladditive A to produce a homogeneous powder, wherein the rare earthmaterial R may include at least one of: a) Nd or b) Pr, and theelemental additive A may include at least one of: a) Nd, b) Pr, c) Dy,d) Co, e) Cu, and f) Fe. Other embodiments of this aspect includecorresponding computer systems, apparatus, and computer programsrecorded on one or more computer storage devices, each configured toperform the actions of the methods. A system of one or more computerscan be configured to perform particular operations or actions by virtueof having software, firmware, hardware, or a combination of theminstalled on the system that in operation causes or cause the system toperform the actions. One or more computer programs can be configured toperform particular operations or actions by virtue of includinginstructions that, when executed by data processing apparatus, cause theapparatus to perform the actions.

The foregoing and other embodiments can each optionally include one ormore of the following features, alone or in combination. The method mayinclude performing the fragmenting and the mixing concurrently.Fragmenting the demagnetized magnetic material may include fragmentingthe demagnetized magnetic material to an average particle size between 1to 4 μm. Fragmenting the demagnetized magnetic material may includeremoving particles with a particle fraction of size bigger than anaverage size of particles in the demagnetized magnetic material from thedemagnetized magnetic material to obtain a low oxygen concentration inthe demagnetized magnetic material. Removing, from the demagnetizedmagnetic material, particles with the particle fraction of size biggerthan the average size of particles in the demagnetized magnetic materialto obtain a low oxygen concentration in the demagnetized magneticmaterial may include sieving.

In some implementations, the method includes mixing the homogenouspowder with another element selected from the rare earth material R orthe elemental additive A. The method may include subjecting the magneticmaterial to at least one of: a) a mechanical treatment or b) a chemicaltreatment, to remove the coating layers and prepare the magneticmaterial without impurities. The method may include harvesting themagnetic material from one or more magnet assemblies by separating awaste magnet part from a non-magnet part included in the magnetassemblies, and extracting the waste magnet part from the non-magnetpart. Fragmenting the demagnetized magnetic material to form the powdermay include fragmenting the demagnetized magnetic material to form thepowder with an average particle size between about 1 micron to about 2millimeters. The method may include further fragmenting the powder to anaverage particle size between about 1 to about 4 microns, andhomogenizing the powder. Homogenizing the powder may includehomogenizing the powder that may include an average particle sizebetween about 1 micro to about 2 millimeters, and mixing the powder witha) the rare earth material R and b) the elemental additive A to producethe homogeneous powder may include mixing the powder with an averageparticle size between about 1 to about 4 micros with a) the rare earthmaterial R and b) the elemental additive A to produce the homogenouspowder. Mixing the powder with a) the rare earth material R and b) theelemental additive A to produce the homogeneous powder may includemixing the powder with an average particle size between about 1 micronto about 2 millimeters with a) the rare earth material R and b) theelemental additive A to produce the homogenous powder, and homogenizingthe powder may include homogenizing the powder that may include anaverage particle size between about 1 to about 4 microns.

In some implementations, the method includes fragmenting the rare earthmaterial R and the elemental additive A separately from fragmenting thedemagnetized magnetic material to form the powder, wherein mixing thepowder with a) the rare earth material R and b) the elemental additive Ato produce the homogeneous powder may include mixing the powder with a)the fragmented rare earth material R and b) the fragmented elementaladditive A to produce the homogeneous powder.

In some implementations, the method may include sintering andmagnetizing the homogenous powder to form a recycled Nd—Fe—B magneticproduct with a remanence and a coercivity at least the same as a wastemagnet part from the waste magnet assembly. Sintering and magnetizingthe homogenous powder to form a recycled Nd—Fe—B magnetic product mayinclude compacting the homogenous powder to form a green compact,sintering the green compact between about 1000° C. to about 1100° C.,and magnetizing the sintered green compact to an inert atmosphere below15° C. to form the recycled Nd—Fe—B magnetic product. The method mayinclude heat treating the sintered green compact between about 490° C.to about 950° C. prior to magnetizing the sintered green compact. Themethod may include exposing the green compact to an inert magnetic fieldbelow 15° C. An atomic percentage of Co in the recycled Nd—Fe—B magneticproduct may be less than or equal to 3%. An atomic percentage of Cu inthe recycled Nd—Fe—B magnetic product may be less than or equal to 0.3%.A combined atomic percentage of Fe and Co in the recycled Nd—Fe—Bmagnetic product may be less than or equal to 77%. A combined atomicpercentage of Nd, Pr, and Dy in the recycled Nd—Fe—B magnetic productmay be greater than or equal to a combined atomic percentage of Nd, Pr,and Dy in a waste magnet part from the waste magnet assembly. A combinedatomic percentage of Nd, Dy, and Pr in the recycled Nd—Fe—B magneticproduct may be less than or equal to 18 at. %. The method may includeadding a lubricant to the powder prior to compacting the homogenouspowder to form the green compact. The coercivity of the recycled Nd—Fe—Bmagnetic product may be between about 0 to about 20% greater than thecoercivity of a waste magnet part from the waste magnet assembly.

In some implementations, the method may include sintering andmagnetizing the homogenous powder to form a recycled Nd—Fe—B magneticproduct with a final remanence and a final coercivity, wherein the finalremanence is about 97% of another remanence of a waste magnet part fromthe waste magnet assembly and the final coercivity is at least 30%greater than another coercivity of the waste magnet part. The method mayinclude sintering and magnetizing the homogenous powder to form arecycled Nd—Fe—B magnetic product with a final remanence and a finalcoercivity, wherein the final remanence is about 95% of anotherremanence of a waste magnet part from the waste magnet assembly and thefinal coercivity is at least 80% greater than another coercivity of thewaste magnet part. The method may include sintering and magnetizing thehomogenous powder to form a recycled Nd—Fe—B magnetic product with afinal remanence and a final coercivity, wherein the final remanence isabout 5% greater than another remanence of a waste magnet part from thewaste magnet assembly and the final coercivity is at least the same asanother coercivity of the waste magnet part.

In some implementations, the method may include sintering andmagnetizing The homogenous powder to form a recycled Nd—Fe—B magneticproduct having a composition substantially of W_(a)R_(b)A_(c), where Wmay include Nd—Fe—B material from the waste magnetic assembly andindices a, b, and c represent atomic percentages of the correspondingcompositions or elements. Mixing the powder with a) the rare earthmaterial R and b) the elemental additive A to produce the homogeneouspowder may include homogeneously distributing the rare earth material Rand the elemental additive A within the demagnetized magnetic material,and sintering and magnetizing the homogenous powder to form a recycledNd—Fe—B magnetic product may include forming the recycled Nd—Fe—Bmagnetic product with a concentration of the rare earth material R and aconcentration of the elemental additive A that increases, on average,surrounding the primary Nd₂Fe₁₄B phase within the recycled Nd—Fe—Bmagnetic product. Forming the recycled Nd—Fe—B magnetic product mayinclude restoring, modifying, and improving a concentration and anelemental composition of a grain boundary phase, on average, at aplurality of grain boundary regions that extend throughout the recycledNd—Fe—B magnetic product. 81≦a≦99.9, 0.1≦b≦19,3−99.9*a(Co)≦c(Co)≦3−81*a(Co), 0.3−99.9*a(Cu)≦c(Cu)≦0.3−81*a(Cu),77−99.9*(a(Fe)+a(Co))≦c(Fe)≦77−81*(a(Fe)+a(Co)),a(Nd)+b(Nd)+c(Nd)+a(Pr)+b(Pr)+c(Pr)>0,a(Nd)+b(Nd)+c(Nd)+a(Pr)+b(Pr)+c(Pr)+a(Dy)+b(Dy)+c(Dy)≦18,a(Co)+b(Co)+c(Co)≦3, a(Cu)+b(Cu)+c(Cu)≦0.3,a(Fe)+b(Fe)+c(Fe)+a(Co)+b(Co)+c(Co)≦77, andb(Nd)+c(Nd)+b(Pr)+c(Pr)+b(Dy)+c(Dy)≧0. The atomic percentages of therare earth material R and the additive material A may satisfy Nd[0.1−19at. %*s(Nd), x]Pr[0.1−19 at. %*s(Pr), y]Dy[0.1−19 at. %*s(Dy), z]Co[0at. %, d]Cu[0 at. %, e]Fe[0At. %, f] where [m,n] means a range fromminimum m and maximum n; s(t) is the atomic percent of element t instarting composition; f(t) is the atomic percent of element t in finalcomposition; x =18−[81, 99.9] at. %*(s(Nd)+s(Pr)+s(Dy)); y=18−[81,99.9]at. %*(s(Nd)+s(Pr)+s(Dy)); z =18−[81, 99.9] at. %*(s(Nd)+s(Pr)+s(Dy));d=3−[81, 99.9] at. %*s(Co); e=0.3−[81, 99.9] at. %*s(Cu); and f=77−[81,99.9] at. %*(s(Fe)+s(Co)).

In some implementations, demagnetizing the magnetic material from thewaste magnet assembly by cyclic heating and cooling of the magneticmaterial may include demagnetizing a waste magnet part from the wastemagnet assembly to fragment the adhesives that bond a waste magnet partmay include the magnetic material to a non-magnet part and to crack atleast one coating layer selected from: an electrolytic black Epoxy, aNi, a Ni—Cu, a Ni—Ni, a Ni—Cu—Ni, or a Zn coating layer of the wastemagnet part. The cyclic heating and cooling may include heating themagnetic material to a Curie temperature of the rare earth material R,and cooling, after to a Curie temperature of the rare earth material R,the magnetic material at a rate of at least 100° C./sec. Mixing thepowder may include mixing the powder with at least three elements of:Pr, Nd, Dy, Co, Cu, or Fe. The elemental additive A may include pure Nd.The elemental additive A may include pure Pr. The method may includeadding a lubricant to the powder prior to fragmenting the demagnetizedmagnetic material.

In general, one innovative aspect of the subject matter described inthis specification can be embodied in a recycled Nd—Fe—B sintered magnetmay include a composition of W_(a)R_(b)A_(c), where waste material W mayinclude material from a waste Nd—Fe—B sintered magnet, rare earthmaterial R may include at least one of: a) Nd or b) Pr, and elementaladditives A may include at least one of: a) Nd, b) Pr, c) Dy, d) Co, e)Cu, or f) Fe, and indices a, b, and c indicate atomic percentages of thecorresponding compositions or elements and have values satisfying81≦a≦99.9, 0.1≦b≦19, 3−99.9*a(Co)≦c(Co)≦3−81*a(Co),0.3−99.9*a(Cu)≦c(Cu)≦0.3−81*a(Cu),77−99.9*(a(Fe)+a(Co))≦c(Fe)≦77−81*(a(Fe)+a(Co)),a(Nd)+b(Nd)+c(Nd)+a(Pr)+b(Pr)+c(Pr)>0,a(Nd)+b(Nd)+c(Nd)+a(Pr)+b(Pr)+c(Pr)+a(Dy)+b(Dy)+c(Dy)≦18,a(Co)+b(Co)+c(Co)≦3, a(Cu)+b(Cu)+c(Cu)≦0.3,a(Fe)+b(Fe)+c(Fe)+a(Co)+b(Co)+c(Co)≦77, andb(Nd)+c(Nd)+b(Pr)+c(Pr)+b(Dy)+c(Dy)≧0.

In general, one innovative aspect of the subject matter described inthis specification can be embodied in a recycled Nd—Fe—B sintered magnetmay include a composition of W_(a)R_(b)A_(c), where waste material W mayinclude material from a waste Nd—Fe—B sintered magnet, rare earthmaterial R may include at least one of: a) Nd or b) Pr, and elementaladditives A may include at least one of: a) Nd, b) Pr, c) Dy, d) Co, e)Cu, or f) Fe, and indices a, b, and c indicate atomic percentages of thecorresponding compositions or elements and the atomic percentages of therare earth material R and the elemental additives A have valuessatisfying Nd[0.1−19 at. %*s(Nd), x]Pr[0.1−19 at. %*s(Pr), y]Dy[0.1−19at. %*s(Dy), z]Co[0 at. %, d]Cu[0 at. %, e]Fe[0 at. %, f] where [m,n]means a range from minimum m and maximum n; s(t) is the atomic percentof element t in starting composition; f(t) is the atomic percent ofelement t in final composition; x=18−[81, 99.9] at.%*(s(Nd)+s(Pr)+s(Dy)); y=18−[81, 99.9] at. %* (s(Nd)+s(Pr)+s(Dy));z=18−[81, 99.9] at. %*(s(Nd)+s(Pr)+s(Dy)); d=3−[81, 99.9] at. %* s(Co);e=0.3−[81, 99.9] at. %*s(Cu); and f=77−[81, 99.9] at. %*(s(Fe)+s(Co)).

The foregoing and other embodiments can each optionally include one ormore of the following features, alone or in combination. The rare earthmaterial R and the elemental additives A may be distributedhomogeneously throughout the recycled Nd—Fe—B sintered magnet such thata concentration of the rare earth material R and a concentration of theelemental additives A increases on average in a mixture of wastematerial W surrounding the primary Nd₂Fe₁₄B phase within the recycledNd—Fe—B sintered magnet. A first atomic percentage of the waste materialW may include between about 99.9 at. % and about 81 at. % and a secondatomic percentage of a combination of the rare earth material R and theelemental additives A may include between about 0.1 at. % and about 19at. %. The recycled Nd—Fe—B sintered magnet may include an average grainsize less than 5 microns. The recycled Nd—Fe—B sintered magnet mayinclude an average grain size less than 2.5 microns. The recycledNd—Fe—B sintered magnet may include a density between about 7.56 g/cm³to about 7.6 g/cm³.

In some implementations, the recycled Nd—Fe—B sintered magnet mayinclude an atomic percentage of Co less than or equal to 3%. Therecycled Nd—Fe—B sintered magnet may include an atomic percentage of Culess than or equal to 0.3%. The recycled Nd—Fe—B sintered magnet mayinclude a combined atomic percentage of Fe and Co less than or equal to77%. The recycled Nd—Fe—B sintered magnet may include a combined atomicpercentage of Nd, Dy, and Pr less than or equal to 18%. The elementaladditive A may include pure Nd. The elemental additive A may includepure Pr.

In general, one innovative aspect of the subject matter described inthis specification can be embodied in a system for harvesting a wasteNd—Fe—B sintered magnet from an end-of-life product, the systemincluding a positioning mechanism that defines a recess to receive andlocate the end-of-life product relative to the positioning mechanism,the end-of-life product including the waste Nd—Fe—B sintered magnet, aseparating station to substantially separate a portion of theend-of-life product containing the waste Nd—Fe—B sintered magnet fromthe remainder of the end-of-life product when the positioning mechanismmoves the respective end-of-life product through the separating station,and a transport station that receives the portion of the end-of-lifeproduct containing the waste Nd—Fe—B sintered magnet from thepositioning mechanism when the positioning mechanism moves therespective end-of-life product to the transport station.

The foregoing and other embodiments can each optionally include one ormore of the following features, alone or in combination. The system mayinclude a loading station, and a loading device that loads theend-of-life product onto the positioning mechanism at the loadingstation. The loading device may orient the end-of-life product on thepositioning mechanism to position the portion of the end-of-life productcontaining the waste Nd—Fe—B sintered magnet for separation from theremainder of the end-of-life product at the separating station. Theloading device may include a robot. The loading device may include afeeder. The transport station may include a reclaim bin that receivesthe portion of the end-of-life product containing the waste Nd—Fe—Bsintered magnet of at least some of the end-of-life products from thepositioning mechanism.

In some implementations, the transport station includes a tool to finishremoving the portion of the end-of-life product containing the wasteNd—Fe—B sintered magnet from the remainder of the end-of-life product.The tool may include a deflection surface. The tool may include anabrasive cutter.

In some implementations, the transport station includes a reclaim binthat receives the portion of the end-of-life product containing thewaste Nd—Fe—B sintered magnet of at least some of the end-of-lifeproducts when the tool finishes removing the portion of the end-of-lifeproduct containing the waste Nd—Fe—B sintered magnet from the remainderof the end-of-life product. The transport station may include a conveyorthat receives the portion of the end-of-life product containing thewaste Nd—Fe—B sintered magnet of at least some of the end-of-lifeproducts when the tool finishes removing the portion of the end-of-lifeproduct containing the waste Nd—Fe—B sintered magnet from the remainderof the end-of-life product. The transport station may include a chutethat receives the portion of the end-of-life product containing thewaste Nd—Fe—B sintered magnet of at least some of the end-of-lifeproducts when the tool finishes removing the portion of the end-of-lifeproduct containing the waste Nd—Fe—B sintered magnet from the remainderof the end-of-life product.

In some implementations, the system includes a base to support thepositioning mechanism, and an aperture in the base at the transportstation to allow the portion of the end-of-life product containing thewaste Nd—Fe—B sintered magnet to fall into the reclaim bin. The systemmay include a discard station that removes the remainder of theend-of-life product of at least some of the end of life products fromthe positioning mechanism. The discard station may include a discardbin. The positioning mechanism may rotate around a center axis to movethe end-of-life products between the separating station and thetransport station. The system may include a base table to support thepositioning mechanism. The system may include bearings located on thebase table that support the positioning mechanism and reduce frictionbetween the base table and the positioning mechanism.

In some implementations, the separating station may include one of aplasma cutter, a water jet, a blade cutter, a band saw, and a shear. Thepositioning mechanism may include turntable defining a plurality ofrecesses each of which receives one of the end-of-life products at aloading station. The system may include a filtered vent to remove wasteparticles from the system. The system may include an inertial separatorto remove waste particles from the system. The system may include a ventto exhaust pollutants from the system. The system may include a heaterthat receives the portions of the end-of-life product containing thewaste Nd—Fe—B sintered magnet from the transport station and heats theportions of the end-of-life product containing the waste Nd—Fe—Bsintered magnet to a temperature above the Curie temperature of themagnetic material. The system may include a cooler that rapidly coolsthe portions of the end-of-life product containing the waste Nd—Fe—Bsintered magnet to facilitate detachment of the respective magneticmaterial from respective subassemblies in the portions of theend-of-life product containing the waste Nd—Fe—B sintered magnet. Thecooler may rapidly cool the portions of the end-of-life productcontaining the waste Nd—Fe—B sintered magnet to 5° C. after the heatingof the portions of the end-of-life product containing the waste Nd—Fe—Bsintered magnet to the temperature above the Curie temperature of themagnetic material.

In general, one innovative aspect of the subject matter described inthis specification can be embodied in a gas mixing apparatus forfragmenting and mixing waste magnetic material including a plurality ofreaction vessels, each of the plurality of reaction vessels may includean internal liner having a plurality of openings defined therein, eachof the internal liners configured to receive magnetic material andfacilitate the circulation of gas around the magnetic material throughthe plurality of openings, and a pump and valve assembly operativelycoupled to the plurality of reaction vessels to control the introductionof gas into the plurality of reaction vessels and to control transfer ofgas between the plurality of reaction vessels.

The foregoing and other embodiments can each optionally include one ormore of the following features, alone or in combination. Each of theplurality of reaction vessels may include a diffusion promotion devicemay include a plurality of apertures defined through the device, thediffusion promotion device operatively coupled to the pump and valveassembly and configured to promote the distribution of gas throughoutthe reaction vessels. Each of the plurality of reaction vessels mayinclude a removable lid. The pump and valve assembly may be operativelycoupled to the plurality of reaction vessels to allow for one or moreof: vacuum pump evacuation of the reaction vessels; venting gas toatmosphere from one of the reaction vessels; pressurizing the reactionvessels; and backfilling one or both of the reaction vessels with gas.The apparatus may include a controller operatively coupled to the pumpand valve assembly to automate the gas mixing processes and gas transferbetween the reaction vessels.

In some implementations, the apparatus includes a gas storage chamber,wherein the gas storage chamber is configured to store gas transferredfrom one of the reaction vessels prior to transfer to the other of thereaction vessels. The gas may be hydrogen or a mixture of an inert gasand hydrogen. One or more of the reaction vessels may include acirculation promoter configured to promote gas flow inside each of thereaction vessels. The circulation promoter may include one of a stirrer,fan, or gas feed. Each of the plurality of reaction vessels may includea separate gas supply line connected between the reaction vessel and thepump and valve assembly. The gas mixing apparatus may be configured toproduce a powder particle size between 1-10 μm from the waste magneticmaterial.

In general, one innovative aspect of the subject matter described inthis specification can be embodied in a hydrogen mixing apparatus forfragmenting and mixing waste magnets to form an optimal powder and/orhydride blend, the apparatus includes a pair of reaction chambers, and agas management component connected to, and interconnecting, the pair ofreaction chambers, the gas management component configured to transfergas between the pair of reaction chambers and to pressurize one of thereaction chambers to a target pressure.

The foregoing and other embodiments can each optionally include one ormore of the following features, alone or in combination. The gasmanagement component may include a pump and valve assembly operativelycoupled to the pair of reaction chambers to control the introduction ofgas into the pair of reaction chambers and to control transfer of gasbetween the pair of reaction chambers. At least one of the reactionchambers may include a thermostatically regulated heater within thechamber. The apparatus may include a carriage assembly configured to bereceived with one of the pair of reaction chambers, the carriageassembly may include one or more bottles containing waste magneticmaterial. The carriage assembly may include a removable cover. Thebottles may include a removable cover, the cover configured to act as afunnel to permit recovered hydride magnet particles to be directedthrough a chute following the hydrogen mixing process. One or more ofthe bottles may include a device that facilitates gas diffusion withinan interior of the bottle. The device may include a cylinder withopenings in a side of the cylinder that allow for the diffusion of gasso the gas reaches the waste magnetic material contained within thebottle.

The subject matter described in this specification can be implemented inparticular embodiments so as to realize one or more of the followingadvantages. In some implementations, a recycling process has low energyconsumption and low virgin material consumption. In someimplementations, recycling Nd—Fe—B magnets may reduce economic and/orenvironmental costs, without diminishing the magnetic performance anddeliverable value of a final product, a fully dense Nd—Fe—B sinteredmagnet. In some implementations, a recycled Nd—Fe—B magnet product mayhave a performance similar to or better than virgin Nd—Fe—B magnets. Insome implementations, a recycled Nd—Fe—B magnet product may include asmuch as 99.9% of the waste starting magnetic material used to create therecycled magnet.

The details of one or more embodiments of the subject matter of thisspecification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages of thesubject matter will become apparent from the description, the drawings,and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-C show an example of a separation machine.

FIG. 2 shows an example of a furnace which processes magnets or magneticassemblies for demagnetization and to remove assemblies from EOLmagnets.

FIG. 3A shows an example of an abrasive jet cleaning device that cleansmagnets.

FIG. 3B shows an example of a hydrogen mixing reactor that breaks wastemagnetic material into particles and mixes the particles.

FIGS. 4A-E, 4H and 4J show reaction bottles which may be placed on acarriage to permit transport of the reaction bottles into and out of areaction chamber.

FIGS. 4F-G show an example of another hydrogen mixing reactor with apair of reaction chambers.

FIG. 4K shows and example of a storage container for the magneticparticles received from bottles.

FIG. 5 is an example of a process for recovering waste magnet andmagnetic material from products, e.g., manufacturing “bulk”,failed/rejected/surplus batches, and/or EOL products, to achieve targetproperties.

FIG. 6 is a graph that shows an example of property ranges for startingmaterials which may be obtained as bulk and/or EOL magnets and forrecycled magnets.

FIG. 7 is a diagram comparing the composition of the original wastemagnetic material, shown in the left column, to the finished recycledmagnet product, shown in the right column, created by the process.

FIG. 8 showing different shapes and coatings of sintered magnets.

FIG. 9 is a block diagram of a computing system that can be used inconnection with computer-implemented methods described in this document.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

According to some implementations, a method is described formanufacturing fully dense Nd—Fe—B sintered magnet using waste magnets,e.g., bulk magnetic material and/or end-of-life (EOL) magnets. Bulkmagnets refer to magnetic material without end product finishing,particularly coating materials. An example of bulk magnet material ismagnetic material discarded as a result of material losses, machining(tailings) and inefficiencies that occur during manufacturing. Anotherterm used in the industry for such material is drop. End-of-life (EOL)magnets refer to magnets and pieces of magnets that include end productfinishing, particularly, coating materials. Examples of EOL magnetmaterials include magnets or pieces thereof that have been harvestedfrom discarded products. For example, magnets that are separated fromtheir magnetic circuitry, assembly, or other substrates but which maystill retain their coatings. An end-of-life product would be a productthat includes an EOL magnet, such as a hard disk drive.

A method for manufacture may reduce the number of activities in thetotal value chain compared to traditional Nd—Fe—B manufacture, e.g.,mining, concentration, oxide production, chloride production, alloyproduction, strip-casting procedures have all been eliminated. A productresulting from the processes described below is a fully dense Nd—Fe—Bsintered magnet that may exhibit high performance characteristics withrespect to remanence (Br), coercivity (iHc), and energy product (BHmax),as described below with reference to the Tables. In someimplementations, the product can be manufactured with equal or greaterremanence (Br), coercivity (iHc), or energy product (BHmax) than thewaste starting material. The new Nd—Fe—B product may exhibit improvedtemperature profile and corrosion resistance compared to the wastestarting material. A method may have low virgin material inputrequirements and low basic operational costs. The process may combine81-99.9% of waste magnetic material and/or magnet and 0.1-19% of rareearth elemental additives, and the process may have a high affinity forrecovery of all elements present in waste magnet, e.g., Nd, Dy, Pr andFe, Co, Cu, Al, Ti, Zr, Gd, Tb, etc., and magnetic performance, e.g.,Br, iHc, or BHmax, etc.

A method for manufacturing fully dense Nd—Fe—B sintered magnet mayinclude: extraction of EOL magnet component(s) from productstructure(s), including, but not limited to, hard disk drives, motors,generators, or loudspeakers; and preparation of magnet and magneticmaterial through mechanical and chemical measures and treatments priorto a method for new Nd—Fe—B sintered magnet product manufacturing. Amethod for Nd—Fe—B sintered magnet product manufacturing may includeremoval of a coating directly from the extracted EOL magnet components.A method may include one or more mixing operations of the resultinguncoated material, at least one of which may include, but is not limitedto, mixing uncoated magnetic material using a hydrogen mixing reactor. Amethod may employ methods for oxygen suppression. A method may includethe addition of new rare earth material in a range of 0.1 to 19% of thestarting material. Further details and optional features of someimplementations include operations that maintain, improve, and/orprovide specific targeted Nd—Fe—B magnet performance characteristics.Such performance characteristics may include desired combinations ofparticle size, alignment, density, energy product (BHmax), coercivity(iHc), and/or remanence (Br).

Some implementations may reduce the need for new rare earth supply whenmanufacturing a recycled product with desired properties. Someimplementations may alleviate rare earth supply risk and end-uservulnerability to rare earth price volatility, play an important role increating a more sustainable magnet supply chain, or a combination of anytwo or more of those. In some implementations, material inputrequirement costs are reduced by utilizing waste magnetic materialinstead of mined virgin material. Resource requirements in terms ofmaterials, waste, pollution, and energy may be reduced with concomitantbenefits.

In some implementations, methods include component recovery of Nd—Fe—Bmagnet contained or embedded in a product structure, such as EOLproducts. In initial processing, which may be characterized as aharvesting phase, a method may include the harvesting of EOL Nd—Fe—Bmagnets from attached assemblies or component materials, which arecontained in or separated from EOL product. In some implementations, theinitial processing includes consolidation of components containing EOLNd—Fe—B magnet and separation of EOL Nd—Fe—B magnet from assemblymaterial in order to increase the concentration of magnet to total mass.The initial processing may detach, fragment, or disintegrate the coatingon the magnet and/or any material, such as adhesives, that secure themagnet to other materials, e.g., magnetic circuit or support chassis.

The initial harvesting processing may be followed by a further step thatincludes a heating and cooling operation, adapted to separate adhesivebonds between magnets and magnetic assemblies, as well as an initial orcomplete breakdown of coatings on the magnets. In some implementations,the harvested magnetic assemblies are loaded into a furnace and exposedto a cyclic heating process. In such a process, the material may beheated above the Curie temperature, for example at 600° C., of theNd—Fe—B sintered magnet, e.g., the point where the magnetic flux isreduced to zero, in order to demagnetize the magnet and weaken or burnany adhesive attached to the magnets or parts thereof. For example, afirst heating cycle may be one in which the materials are heated to atleast 400° C. or to a sufficiently high temperature and long enough tocause the sintered magnet to demagnetize. A second heating cycle may beperformed at a sufficiently high temperature, e.g., 650° C., and/or longenough to ensure that the adhesive is weakened or destroyed. Rapidcooling at the end of the first or second heating cycles may be used toaid in the detachment of the rare earth magnet from any assembly and tocompletely or partly fragment and/or delaminate any coating layercovering the magnet. The heating and cooling process may also includedemagnetization and/or fragmentation and/or delamination of the coatingof EOL magnets that have already been separated from other parts orassemblies, such as support chassis, magnetic circuits, or other parts.

In some implementations, the repeated heating of a magnet attached toanother part, e.g., an assembly, a magnetic circuit, a support, or otherpart, at 650° C., with a hold time of 1 hour followed by rapid coolingto 5° C., is effective to remove the magnet from magnetic assemblies, toweaken or destroy any adhesive and to crack any coating layer on themagnets.

The heating process may be conducted with air, argon, or any other inertatmosphere. Heating may be performed using any suitable techniqueincluding, for example, resistive heating, radio frequency heating,convection, microwave heating, gas combustion heating, or immersion intochemical hot bath or other convection heating. Magnets may then beseparated using a separation device and collected and transported usinga suitable conveyor.

A process whose principal purpose is the removal of coatings of magnets,which may be characterized as surface removal process, may employmechanical surface removal techniques, for example the use of anabrasive jet. The surface removal process may include centrifugal drum,grinding, or immersion into a hot chemical bath.

In some implementations of the coating removal phase, for 100 kg ofmixed waste magnets, 15 minutes of abrasive jet using steel shot havinga diameter of 1 mm was found to be sufficient to remove a protectivelayer on NiCuNi, aluminum, black epoxy, and zinc coated magnets ofdifferent shapes. This protective layer may be collected by sieving forthe purpose of recycling and the extracted magnets are forwarded forfurther processing.

The atmosphere and temperature may be controlled during abrasive jetprocessing. In some implementations, abrasive jet, e.g., shot blasting,processing may be performed in an air, argon, or other inert atmosphereat 5° C. to 600° C. with humidity preferably in the range of 0-35%. Insome examples, the mass loss of waste sintered Nd—Fe—B material duringthis operation was less than 1%. The duration of processing, velocity ofparticulate material, e.g., shot, and/or other parameters may beselected to limit mass loss to no more than 1%. In some implementations,the parameters may be chosen to ensure a mass loss of no more than 10%and, in some implementations, no more than 5%.

The mechanically uncoated magnets may be chemically processed in 1-5%diluted HCl or HNO₃ to further remove any oxide layer from the surfaceof waste magnet. The implementations are not limited to these optionsand in some implementations other agents may be used to remove oxide,for example, CuSO₄. The mass loss during this process may be held in therange of 0.1-5%. Preferably the time, temperature, and concentration arechosen such that the mass loss is no more than 10% and, specifically, nomore than 20%.

In a mixing phase, bulk magnets are mixed with additional raw materialto achieve desired final properties in a finished product made from thematerials. The mixing process may include crushing, grinding, milling,or the use of hydrogen to break down materials to coarse powder. In someimplementations, the magnets, e.g., Nd—Fe—B or 2:17 type magnets, areprocessed into a powder using a hydrogen mixing reactor, and the powdermaterial is combined in situ with additives to restore or improveremanence, energy product, and/or density.

In some implementations, additional magnetic material may be added towaste magnetic material to recover or improve the performance of themagnets. The additional magnetic material may be a combination of a rareearth, RE, e.g., Nd, Pr, Dy, Gd, Tb, La, Ce, Yb, Ho, or Eu, and atransitional metal, TM, e.g., V, Cr, Mn, Fe, Co, Ni, Cu, Y, or Zr. Forinstance, the atomic percentages of the additional magnetic material mayhave a formula satisfied by equation (1) below.Nd[0.1−19 at. %*s(Nd),x]Pr[0.1−19 at. %*s(Pr),y]Dy[0.1−19 at.%*s(Dy),z]Co[0 at. % ,d]Cu[0 at. %,e]Fe[0 at. %,f]  (1)

Where [m,n] means a range from minimum m and maximum n, s(t) is theatomic percent of element t in starting composition, f(t) is the atomicpercent of element t in final composition, x=18−[81, 99.9] at.%*(s(Nd)+s(Pr)+s(Dy)), y=18−[81, 99.9] at. %* (s(Nd)+s(Pr)+s(Dy)),z=18−[81, 99.9] at. %*(s(Nd)+s(Pr)+s(Dy)), d=3−[81, 99.9] at. %* s(Co),e=0.3−[81, 99.9] at. %*s(Cu), and f=77−[81, 99.9] at. %*(s(Fe)+s(Co)).

Additional requirements include one or more of the following: a) Virginmaterial added, NdpPrqDyr, need be in the range of 0.1≦p+q+r≦19 at. % offinal product, and T≧min(R, 18), where T=f(Nd)+f(Pr)+f(Dy) andR=s(Nd)+s(Pr)+s(Dy); b) p+q+r≧X, where X is at. % RE (Nd, Pr, Dy)removed from original magnet; c) T≦18%; d) f(Nd)+f(Pr)>0, where f is anat. % fraction of the final product; e) f(Nd)+f(Pr)+f(Dy)<=18; f)f(Co)<=3; g) f(Cu)<=0.3; h) f(Fe)+f(Co)<=77; or i) f(Dy)+f(Nd)+f(Pr)>=R.

Processes for mixing include milling, cutting, high energy ball milling,roller milling, sawing, jet milling, tumbling, shaking, jaw crushing,and hydrogen mixing. In some implementations, hydrogen mixing is aprocess for homogenizing starting material waste magnets and fresh rareearth elemental additives. In the hydrogen mixing process, hydrogenenters the φ phase, e.g., Nd₂Fe₁₄B, and rare earth rich grain boundariesof waste magnets and reacts with the rare earth elements forming ahydride with hydrogen being trapped in the crystalline structure. Thecrystal structure expands as a result of hydrogen absorption and hydrideformation causing the brittle structure to fracture. The result can beeffective for mixing and, at the same time, for fragmentation of thewaste magnet and additive materials.

The term “fragmentation” as used herein comprehends any type of divisionof solid materials including mechanical, chemical, thermal, radiative,or any suitable process including combinations thereof. The degree offragmentation may be from coarse division to complete disintegration toa fine powder.

In some implementations, a method provides for the addition of 0.1 to 19wt. % of one or more rare earth elemental additives to a composition ormethod described herein. In another aspect, a method provides for theaddition of about 0.1 wt. %, about 0.2 wt. %, about 0.3 wt. %, about 0.4wt. %, about 0.5 wt. %, about 1 wt. %, about 2 wt. %, about 3 wt. %,about 4 wt. %, about 5 wt. %, about 6 wt. %, about 7 wt. %, or about 8wt % of one or more rare earth elemental additives or a combination ofone or more rare earth elemental additives to a composition or methoddescribed herein. In yet another aspect, a method provides for theaddition of about 0.1-0.5 wt. %, about 0.1-1 wt. %, about 0.5-1 wt. %,about 1-2 wt. %, about 1-3 wt. %, about 1-5 wt. %, about 1-8 wt. %,about 2-4 wt. %, about 2-6 wt. %, about 3-5 wt. %, or about 3-8 wt. % ofone or more rare earth elemental additives or a combination of one ormore rare earth elemental additives to a composition or method describedherein.

In some implementations, the method includes no more than 0.1-1 at. %,preferably 1%, of Pr, 25 wt. %, /Nd, 75 wt. %, rare earth elementaladditives. In situ production of a desired fine and impurity-free powdermixture using hydrogen mixing reactor, together with essential rareearth elemental additives and/or hydride additions of fresh elements,may be effective for recovering or improving magnetic performance fromwaste Nd—Fe—B-type sintered magnetic materials. Addition of 0.1 wt %-19wt %, preferably 1%, of additive elemental additives may be included torestore or improve the magnetic performance and physical properties,e.g., density or corrosion resistance, of the magnetic material. Theadditions and waste magnetic material are loaded in the hydrogen mixingreactor to generate a coarse powder mixture of rare earth includingPr₇₅Nd₂₅H_(x), where x is ranging from 1 to 3 mole fractions.

The hydrogen mixing process may be performed at 20-150° C. at 1 to 60bar pressure under a hydrogen atmosphere. After that, the material maybe heated, preferably in situ, to 550-600° C. to partially degas themixture. The average particle size generated by the mixing step may bein the range of 1 μm to 2000 mm. If a pressure of 50 bar is used, theaverage particle size may correspond to a grain size, e.g., 2-8 μm,present in the waste magnetic material, and powders in the range of 500μm to 2000 mm that have not reacted with hydrogen due to oxidation. Thepowder may be sieved to remove the oxidized coarse rare earth powders.

In some implementations, the hydrogen mixing process employs a highenough pressure to ensure that particles are small enough for a finalmagnet and the jet milling operation can be skipped. In this example,the sieving to remove larger particles, thereby to remove particles withhigher concentration of oxygen, may be advantageous. The sieving iseffective because the oxides constitute a harder fraction of therecovered material from the magnet and resist reduction to smallerparticle sizes.

Further mixing and homogenization of the magnetic powder mixture may betransferred to a roller mill for further homogenization of the mixture.The milled material may be lubricated, for example, with 1% of Znstearate, during roller milling. After the roller milling step, wastemagnetic powders may be sieved to further remove any remaining rareearth oxide. In some implementations, the sieving may be selective toremove particles bigger than 500 μm.

The lubricant used for roller milling may have low oxygen content and/orcontain a binder. Examples of the lubricant include amide, e.g.,oleamide or amide, or other lower carbon-hydrogenate esters or fattyacid, such as oleic acid.

Powders may be further homogenized by jet milling. In someimplementations, the jet may be formed using air or an inert gas such asHe, Ar, or N. The jet milling may be performed for such time, e.g., 1-4hours, and at such velocity so as to homogenize the mixture and furtherbreak down aggregates of single grains to 1-4 μm. In someimplementations, the jet milling may be completed in 24 hours or less.

In some implementations, an 80% reduction in time for the jet milling ofNd—Fe—B powders from waste may be observed compared to jet milling ofNd—Fe—B elemental additives. The average particle size of the wastemagnets may be in the range of 4-10 μm. During jet milling, theaggregates were broken to single grains while an oxidized rare earthpowder remained coarse. By removing the oxidized rare earth coarsepowder, the amount of oxygen incorporated in the waste starting magneticmaterial can be reduced and more preferably suppressed in the finalrecycled sintered magnet. This phase may be done preferably under inertatmosphere, for example using Ar gas, free of any oxygen contamination,with the purpose of homogenizing the mixture of waste magnetic powderand fresh addition of (RE(TM)_(x)) elemental additives and break thesegregated single grains along grain boundaries. RE (rare earth) refersto a combination of any Nd, Pr, Dy, Tb, Y, La, or Sm and TM(transitional elemental additive material) refers to a combination ofany Co, Ni, V, Nb, Mo, Ti, Zr, Al, Cu, Ga, or Fe.

After the particle reduction, mixing, and sieving are completed, thepowder may be aligned and pressed to form a green compact in air or aninert atmosphere. A lubricant may be applied to the powder prior topressing and aligning. The green compact may be pressed and aligned in amagnetic field. Then the green compact may go directly on to sinteringin the range of 1050-1100° C. for 5 hours of holding time, followed byheat treatment at 900° C. for 5 hours and 550° C. for 3 hours. Theselection of sintering temperatures may depend on the amount of totalrare earth additions added prior to the hydrogenation/mixing steps.

In some implementations, processes for cost-effective, scalable recoveryof waste magnetic material may be provided. A method may includemechanical automated processes for harvesting EOL magnet. The processesmay provide a harvesting phase, which provides for the effective andrapid separation of EOL waste magnet from other material assembliesand/or attachments, and the collection/consolidation of the EOL magnet.A separation aspect of the harvesting process may include a cyclicheating and cooling process that accomplishes demagnetization andseparation of adhesive bonds.

The processes can be applied to EOL magnets that may bear coating.Coatings can be removed by mechanical means to minimize contaminationand to preserve the high recovery concentration of magnetic material.High recovery concentration of uncoated magnetic material may beattended by lower cost since the use of primary CO₂, CO, SO₂, NO_(x)energy and materials may be significantly reduced, providing a greenerprocess using the described methods.

The processes may provide for the expeditious restoration of magneticperformance by the addition of elemental additives, hydride, or otheradditives in a series of mixing phases to produce recycled sinteredmagnet with same or better magnetic performance than waste startingmaterial. The described processes may prevent the loss or degradation ofmagnetic performance relative to the starting material by using 0.1-19wt %, preferably 1 wt %, of raw/virgin/fresh additives in combinationwith 81-99.9 wt %, preferably 99 wt %, bulk material or uncoated EOLmagnet.

In some implementations, hydrogen mixing may be used advantageously tofacilitate homogenization of bulk material and/or EOL magnets with freshelemental additives. This may be followed by jet milling, which may beused for further homogenization with supplemental materials, e.g., rareearth oxides or Nd/Pr, in a process that is amenable to cost efficientscalable processing. Other implementations may include milling, rollermilling, high energy ball milling, tumbling and other mixing steps.

FIGS. 1A-C show an example of a separation machine 100. The separationmachine 100 receives EOL articles, such as hard disks, and generates aflow of materials that has a high concentration of the magnet materialof interest. The separation machine 100 may include a control unit 20that controls the operation of the separation machine 100. A turntable4, driven by a drive 12, rotates around a center 6 on bearings 13supported on a base table 19.

In some implementations, hard disk drive (HDD) units 14 are loaded at aloading station 11 and affixed on a turntable either by a robotpositioning device 16, a feeder, conveyer, or manually by a worker. Theloading and affixing are effective to orient the HDD units 14 to be cutat a cutting station 21 by a plasma cutter, water jet, or blade cutter,e.g., that sends a pressurized gas such as N, Ar, or O through a smallchannel that is shielded by an inert gas fed through shielding-gastransport pipe 5, fixed at a particular point of the base table 19. Forexample, the turntable 4 rotates around the center 6 and moves the HDDunits 14 from the loading station 11 to the cutting station 21 where theHDD units are cut to create HDD corners that include magnetic materialfrom the HDD units 14.

In some examples, a plasma cutter may include a nozzle 17, positionedabout two includes above an HDD unit, that ejects the plasma to removethe HDD corners form the HDD unites. The nozzle 17 may receive gas froma plasma control unit through a gas line 18.

In some implementations, the separation machine 100 may employ a bandsaw, or a shear at the cutting station. A shear operation may be alteredto minimize pinching of the substrate that may restrict extraction ofthe magnet, damage to the recovered magnet, crushing of the HDD unit 14corner portion, or any combination of two or more of these.

If not fully separated by the cutter, a deflection surface may furtherapply a force against the corner until it separates from the rest of theHDD unit, such as a downward facing deflection surface over an aperture8 in the base table 19 above the corner reclaim bin 7 which permits theHDD corners to drop into the corner reclaim bin 7. In someimplementations, an abrasive cutter, or an abrasive jet cutter, such asa water jet or other kind of cutting tool, may be used to separate thecorner from the rest of the HDD unit 14.

A filtered vent 1 with a filter such as a HEPA filter 2 may be providedfor particulate management. Other particulate management devices such asinertial separator 3 may be provided. Pollutants may be drawn through adowndraft vent 15.

The HDD units 14 may be held in a recess 24 of the turntable 4, shown inFIG. 1C, by gravity because the recesses 24 may be shaped such that theHDD units 14 are precisely oriented by their engagement with theturntable 4 within the recess 24. The recess, 24, can be modifiedaccording to the type of assembly which contains a magnet, e.g., motor,windmill assembly, etc. The HDD units 14 pass through the cuttingstation 21 which may fully or partly separate the corner that has themagnets to be recovered. The separated corner drops through the cornerdrop opening 8 into a corner reclaim bin 7 while the rest of the HDDunit drops through opening 10 into discard bin 9.

In some implementations, a chute or conveyor may be provided totransport HDD corners, or other magnet assemblies, to a location forfurther processing instead of the corner reclaim bin 7. In someexamples, the HDD corners may be recovered in batches and transportedfor processing.

FIG. 2 shows an example of a furnace 40 which processes magnets ormagnetic assemblies for demagnetization and to remove assemblies fromEOL magnets. For instance, the HDD unit corners may be transported byconveyor 47 into the furnace 40. The furnace 40 is capable of reachingtemperatures above the Curie temperature of the magnetic material usingheaters 43, which may be electric, as shown with heating elements 44inside ceramic sleeves 45, or any other suitable form of heater.Alternative heating methods may be used including resistive, radiofrequency (RF), convection, microwave heating, gas combustion, immersioninto chemical hot bath, any other appropriate heating method, or acombination of any two or more of these. Ductwork 46 may provide for acontrolled atmosphere, such as inert gas, over the heated HDD corners orother waste material containing magnets to further suppress theprogression of magnet oxidation.

The furnace 40 may include an insulated housing 42 with an exterior wall42′. For example, the insulated housing 42 may reduce the amount of heatthat escapes from the furnace 40 and/or protect objects outside of thefurnace 40. Interior seals 41, 41′ may reduce the amount of heat thatescapes from the furnace 40.

The furnace 40 may be any type of heater configured to heat wastemagnets and magnetic assemblies directly, substantially withoutatmospheric contamination so as to cause the detachment of the magnetsfrom subassemblies and other non-magnetic material. The heating combinedwith subsequent fast cooling may serve to facilitate initial cracking ofany magnet coating on a magnetic assembly. Demagnetization of themagnets may be ensured by heating at least to the Curie temperature,e.g., 320° C., of the magnetic material without an applied field.

The furnace 40 may have inner walls that define a sealed heating spacein fluid communication with the ductwork 46 that provides a controlledinert or air atmosphere. The Curie temperature may be between 310° C. to900° C. depending on the composition of the magnetic material. The Curietemperature, or a temperature in excess thereof, may be held to ensurethe release or destruction of adhesives holding magnets to other partsof the magnetic assemblies, e.g., HDD unit corners containing magneticcircuit elements and/or supports. A rapid cooling, for example to 5° C.,may follow the heating in order to further facilitate detachment ofmagnets from their subassemblies, subsequent fracturing of the coating,or both. The heating and cooling may be performed iteratively inmultiple cycles or they may be performed once.

FIG. 3A shows an example of an abrasive jet cleaning device 60 thatcleans magnets 79. The abrasive jet cleaning device 60 has a frame 67that supports an entering conveyor 63 that feeds the magnets 79 into arotating drum 64. The drum 64 rotates to expose surfaces of the magnets79 to jets of abrasive emanating from the jet nozzles 66.

Belt grinding rolls 75 may be provided to ensure the movement of themagnets 79 and their disaggregation to ensure material, such asadhesives and other magnet coatings, is removed from the magnets 79. Thetreatment of the magnets 79 by the abrasive jet cleaning device 60 maybe effective for removing coating layers including, but not limited to,NiCuNi, Al, Zn, and electrolytically deposited black epoxy materials.The rollers 75 may rotate in a direction that is the same as that of thedrum 64 so that magnet adjacent surfaces move in a direction oppositethat of the surface of the drum 64. The rollers 75 may further removesurface material from the magnets. The use of the rollers 75 with thedrum 64 may more evenly expose the surfaces of the magnets 79 to theshot blast treatment of the jet nozzles 66.

A dust/shot collection trough 57 receives shots and particulates fromcoatings, which may then be subjected to sieving, or other size ordensity-separation processes, to recover removed coating material andreuse the abrasive particulate, e.g., shot, which is conveyed by aconveyor 68 to a feeder/generator 69 that generates the abrasive jetsejected from nozzles 66.

Once the excess material is broken off of the magnets 79, an exitconveyor 70 removes the magnets from the jet cleaning device 60. An airwasher 65 may remove any loose material off of the magnets 79 while theexit conveyor 70 removes the magnets from the jet cleaning device.

The abrasive jet cleaning device may include a control cabinet is shownat 71 to control the environment, e.g., processing time, atmosphere,speed, etc., for the jet cleaning device.

Magnet coatings may be completely removed by cleaning the surfaces withan abrasive jet that removes a portion, or all, of the surface of themagnets by ablation. In some implementations, the abrasive can be steelshot, tungsten carbide, ceramic, or steel grit. The size of theparticles may be about 1 mm. The abrasive jet cleaning device 60 canreceive waste magnets and substantially remove the surface or protectivecoatings from the waste magnets without oxygen contamination of thewaste magnets, before further processing of the waste magnets. Theatmosphere around the magnets may be a controlled inert atmosphere suchas Argon.

The magnets 79 may be processed in the abrasive jet cleaning device 60at temperatures between about 5° C. and 600° C. with a humidity levelbetween about 1-35% relative humidity (RH).

In some implementations, the surface removal process is performed for aperiod of time effective to remove less than 5% of the mass of themagnets. In some implementations, the surface treatment is performed fora period between about 15 minutes and about 5 hours.

FIG. 3B shows an example of a hydrogen mixing reactor that breaks wastemagnetic material into particles and mixes the particles. In someimplementations, the hydrogen mixing reactor mixes elemental additiveswith the particles. The hydrogen mixing reactor may create particleswith a target average diameter of between about 1 micron to about 2 mm,or between about 4 to about 7 microns. The hydrogen mixing reactorincludes two vessels 102, 104, placed in mixing chambers 122, 124respectively, that each has inner linings 110 that hold the magneticmaterial and facilitate the circulation of gas around the magneticmaterial through apertures in the inner linings 110. The filling of oneof the vessels 102, 104 with hydrogen gas while the vessel contains rareearth materials causes the fragmentation of the magnetic material due tohydrogen mixing. Exposure to hydrogen gas can last for between about 1to 40 hours. The exposure may be for shorter or longer periods and thepressure and temperature may be selected based on process engineeringrequirements, other processing stages used to achieve a targetparticulate size, other processing stages used to achieve a targethomogenous mixture, or any combination of two or more of these.

Diffusion promotion devices 112, such as snorkels or pipes, withapertures, may be used to ensure that hydrogen mixing causes thebreakdown of the magnets in the reactor vessels 102, 104, and that thepile-up of particulate matter does not prevent some of the magneticmaterial from exposure to the hydrogen gas. Circulation promoters (notshown) such as stirrers, fans, or gas feeds may help promote hydrogengas flow in the vessels 102, 104. Magnetic material that falls throughthe apertures of the inner lining 110 may be stirred by a stirrerlocated at the bottom of the respective vessel 102, 104.

A removable lid 114 may be provided for the introduction of magnets intothe vessels 102, 104. For example, after the magnets 79 are cleaned inthe abrasive jet cleaning device 60 shown in FIG. 3A, the magnets may beplaced in the vessels 102, 104 shown in FIG. 3B. Magnetic material maybe transferred into the inner linings 110 by a conveyor or manually,with or without a controlled environment, e.g., after the magnets arecleaned in the abrasive jet cleaning device 60. A small fraction of rareearth transitional elemental additive material may be added to the innerlinings 110 to bring the properties of a final product made from themagnets to a predefined specification remanence, energy product, and/orcoercivity. In some examples, an additive may be added to crushed wastemagnet material after mixing to adjust the properties of the finalproduct. Some examples of the additive material may include Nd, Pr, Dy,Gd, Tb, La, Ce, Yb, Ho, or Eu.

The vessels 102, 104 may withstand a predefined pressure. For instance,the hydrogen mixing reactor may include a vacuum pump. In someimplementations, the pressure may be increased up to 60 bar. The vessels102, 104 may also withstand lower pressures. The vessels 102, 104 mayhave thermostatically controlled heaters 116 and pressure regulationcontrols.

The hydrogen mixing reactor includes gas source connections 138 thatintroduce hydrogen or other gases into the vessels 102, 104 through apumping assembly 128 and a valve assembly 133. The pumping assembly 128,the valve assembly 133 a gas management component 144, or a combinationof two or more of these, may feed gas directly into the diffusionpromotion devices 112, to ensure full volumetric perfusion of themagnetic material in the vessels 102, 104. In some examples, the pumpingassembly 128 and the valve assembly 133 may connect the vessels 102,104, allowing for vacuum pump evacuation of the vessels 102, 104, e.g.,for degassing or primary loading of gas, pumping gas from one vessel tothe other, e.g., to reclaim hydrogen gas, venting to atmosphere, e.g.,using ambient connections 132 to the external atmosphere, pressurizingthe vessels 102, 104, backfilling one or both of the vessels 102, 104with inert gas, performing other reclamation processes or combinationsof two or more of these. A controller 140 may be connected to the valveassembly 133 and the pump assembly 128 to automate the hydrogen mixingprocesses and hydrogen transfer between the vessels 102, 104.

During the hydrogen mixing process, magnetic particles fall from thevessels 102, 104 through chutes 126 into a chamber 120. The magneticparticles may be removed from the chamber 102 for further processing. Insome implementations, press-withstanding valves may be employed at theopenings between the chutes 126 and the vessels 102, 104.

In some implementations, one of the vessels 102, 104 is made gas tightand evacuated using the gas management component 144. The selectedvessel 102, 104 may then be filled with hydrogen from a gas source,e.g., through the pumping assembly 138, to prepare the selected vessel102, 104 for mixing and fragmentation of waste magnetic material. Aftermixing and fragmentation, the hydrogen may be transferred by the gasmanagement component 144 to the other vessel 104, 102, e.g., byevacuating the hydrogen from the selected vessel 102, 104 andtransferring the hydrogen to the other vessel 104, 102. As each vessel'scontents are subjected to hydrogen mixing, the hydrogen can be recoveredand transferred to the other vessel 102, 104 and the process of hydrogenmixing is repeated in the other vessel.

In some implementations, a gas storage chamber is included in the gasmanagement component 144 and the hydrogen evacuated from one of thevessels 102, 104 is temporarily stored in the gas storage chamber (notshown) prior to transfer to the other vessel 102, 104, e.g., betweenhydrogen mixing cycles. The use of the gas storage chamber may allow thehydrogen mixing reactor to include only one vessel. In some examples,the hydrogen mixing reactor may include more than two vessels. The gasstorage chamber may include multiple chambers constituting respectivestages with volumes chosen to maximize the energy economy for transferof gas to and from the chambers and the vessels 102, 104 by minimizingthe pressure drop or elevation during transfer.

FIG. 4A shows a set of four reaction bottles 212 on a carriage 216,which permits transport of the reaction bottles 212 into and out of areaction chamber, e.g., one of the reaction chambers 202, 202′ shown inFIG. 4F. The reaction chambers 202, 202′ may be used in conjunction withor instead of the hydrogen mixing reactor shown in FIG. 3B. In someexamples, the reaction bottles 212 may be used with the hydrogen mixingreactor shown in FIG. 3B, e.g., as the vessels 102, 104. For example,the gas management component 144 may fill the bottles 212 with inertgas, e.g., Ar or N, that are subsequently filled with magnets. Magnets206, e.g., to be hydrogenated, are loaded from a transfer chute 208 intothe reaction bottles 212. The magnets 206 may be loaded into thereaction bottles 212 in an inert atmosphere, to prevent thecontamination of the magnets 206 such as by oxygen.

In some implementations, a small fraction of rare earth transitionalelemental additive material may be added to the reaction bottles 212.The rare earth transitional elemental additive material may be selectedto bring the properties of a final product, produced from the magnets206 and the rare earth transitional elemental additive material, to apredefined specification remanence, energy product, and coercivity. Insome examples, a hydride of the rare earth transitional elementaladditive material may be added to the hydrogenated magnets 206 aftermixing and fragmentation of the recovered magnets.

Each of the reaction bottles 212 may include a snorkel 213 or anotherdevice that facilitates gas diffusion in the reaction bottles. Forexample, the snorkels 213 may be a cylinder with openings in the sidethat allow for the diffusion of gas, so the gas reaches magnetspositioned in the center of each bottle 212.

The bottles 212 and the snorkels 213 may be open at the top to allowhydrogen gas to enter the bottles 212 and the snorkels 213 and contactthe magnets 206 contained within the bottles 212 and/or to allow loadingof the magnets 206 into the bottles 212.

When the magnets 215 are positioned within the bottles 212, shown inFIG. 4B, a transfer cover 214 may be attached to the carriage 216 toisolate the bottles 212 and their contents from external atmosphere. Thecontainer formed by the cover 214 and carriage 216 may not allow for gasleakage so that its internal volume can maintain an atmosphere of inertgas preventing ambient air from contacting the magnets 215. Forinstance, after the bottles 212 loaded in the inert atmosphere, thebottles 212 may be covered by the cover 214, and the carriages 216stored outside the space with the inert atmosphere. For example, FIG. 4Eshows an example of a loaded bottle 212 prior to the placement of theloaded bottle 212 onto the carriage 216 and the cover 214 on top of theloaded bottle 212. The bottles 212 may be loaded while on the carriage216 or may be loaded and then placed onto the carriage 216.

FIGS. 4F-G show an example of another hydrogen mixing reactor with apair of reaction chambers 202, 202′. The reaction chambers 202, 202′ areconnected to, and interconnected by, a gas management component 144 asdiscussed above. The gas source 138 may provide respective connectionsfor multiple gases such as inert gas and hydrogen. The ambientconnection 132 may provide a vent to atmosphere. The gas managementcomponent 144 operates as described above with reference to FIG. 3B inthat it transfers gas from one reaction chamber 202 to the other 202′and vice versa, instead of between the vessels 102, 104.

A covered carriage 260, e.g., the carriage 216, is rolled into a firstone of the reaction chambers 202 while hydrogenation is occurring in theother reaction chamber 202′. Once the covered carriage 260 is in thereaction chamber 202, the cover 214 is removed from the carriage 260 anda hatch 252 on the reaction chamber 202 is closed. The chamber 202 maythen be filled with inert gas.

The gas management component 144 may supply, to the reaction chamber202, hydrogen from a hydrogen source to achieve a required pressure. Forinstance, when the hydrogenation in the reaction chamber 202′ iscomplete, the gas management component 144 transfers hydrogen from thereaction chamber 202′ into the reaction chamber 202 and pressurizes thereaction chamber 202 to a target pressure. The gas management component144 may initiate hydrogenation in the reaction chamber 202 byintroducing the hydrogen gas, e.g., pressurized hydrogen gas, from thereaction chamber 202 into the bottles 212 through the covers 232 orother openings in the bottles.

The hydrogen mixing process may create magnetic particles with anaverage diameter of between about 1 micro to about 2 mm, e.g., when thehydrogen mixing reactor performs an initial mixing process, or betweenabout 4 micro to about 7 micro, e.g., when the hydrogen mixing reactorperforms a second mixing process. In some examples, the hydrogen mixingreactor shown in FIGS. 4F-G may perform both processes, the hydrogenmixing reactor shown in FIG. 3B may perform both processes, or one ofthe reactors may perform one process and the other reactor may performthe other process. For instance, the hydrogen mixing reactor shown inFIG. 3B may perform the first mixing process and the hydrogen mixingreactor shown in FIGS. 4F-G may perform the second mixing process.

The gas management component 144 may evacuate, e.g., completely, gasfrom the chamber 202′ and place the gas in the chamber 202, for useduring processing in the chamber 202, or in a storage chamber or vessel.A thermostatically regulated heater 257 within the chamber 202, shown inFIG. 4G, may be regulated by a controller to provide a targettemperature.

As the hydrogenation process proceeds in the reaction chamber 202, thegas management component 144 backfills the reaction chamber 202′ withinert gas. The hatch 252′ to the reaction chamber 202′ is then opened,as shown in FIG. 4G, and a cover 214′ is placed on the carriage 260′.The hydride magnet material, now reduced to particles, then moves outfrom the reaction chamber 202′ in the carriage 260′.

After the hydrogenation is completed in the chamber 202, the gasmanagement component 144 evacuates the excess hydrogen gas from thechamber 202. For instance, the hydrogenation process may begin again forone or more bottles 212 placed in the chamber 202′.

In some implementations, the bottles 212 can be closed with a cover 232,shown in FIGS. 4C-D and 4J, that acts as a funnel to permit recoveredhydride magnet particles to be directed through a chute 237 when a valve234 is open, e.g., when the bottle 212 is in the inverted position. Thecover 232 may be removed, e.g., to allow the magnets 206 to enter thebottles 212, and placed on the respective bottles 212 afterward.

Referring to FIG. 4J, in an inert atmosphere, the covers 232 arepositioned on the bottles 212 and the bottles can be sealed and removedfrom the inert atmosphere without the need for the cover 214. Thebottles 212 can be transported by the carriage 216 or individually.

FIG. 4K shows and example of a storage container 240 for the magneticparticles received from the bottles 212. The valves 234 on the bottles212 accept a nozzle 265, included in the storage container 240, to seala manifold 267 to the snorkels 213 in the bottles 212. A blower 266feeds inert gas through the manifold 267 and into the snorkels 213 toremove magnetic particles from the bottles 212 into the storagecontainer 240. The inert gas may circulate back into the storage chamber240 after entering one of the bottles 212.

The inert gas may flow out of the snorkels 213 in a tangential/radialflow, as shown in FIG. 4H which is a cross section of a bottle 212 and asnorkel 213. The arrows show the tangential pattern of the inert gasejected through tangentially-aimed slots in the snorkel 213. Thetangential pattern of the inert gas flow may help remove particles fromthe inside walls of the bottle 212 and facilitate fully emptying themagnetic particles from the bottles 212.

The valve 234 may have a gate configuration, e.g., to permit the entryof the nozzle 265 into the bottle 212. A cover 268 may be place on thenozzle 265 to seal the storage container 240 when the bottles 212 areremoved.

FIG. 5 is an example of a process 500 for recovering waste magnet andmagnetic material from products, e.g., manufacturing “bulk”,failed/rejected/surplus batches, and/or EOL products, to achieve targetproperties. The process 500 may be performed using one or more of thesystems described above.

At S10, a conveyor orients the products with respect to a cutter andfeeds the products through the cutter. The magnet-containing portion, orcut, of the products is separated from the rest of the products and themagnet-containing portion is combined in a batch with othermagnet-containing portions “harvested” from the same or similarequipment.

At S20, the magnet-containing portions, or cuts, are conveyed to asystem that performs separation, demagnetization, and primary fracturingof coating in which the magnet-containing portions are heated and thencooled to cause the separation of any adhesive on the magnet-containingportions, used to attach magnets to respective substrates, such as partsof a magnetic circuit or assembly, from the magnetic material. Thisprocess may substantially recover the entire magnet from themagnet-containing portion or assembly and may not break the recoveredmagnets further.

In some implementations, the heating and cooling may be effective todisrupt or partly fracture a coating, such as a nickel-copper-nickelcoating sometimes used on Nd—Fe—B magnets. Some coatings, such asphosphate, lacquer, or polymer, may be completely destroyed duringheating.

The heating and cooling cycles may be repeated multiple times or onlyonce. The system may heat the magnet-containing portions to atemperature around 600° C. and then cool the magnet-containing portionsto a temperature around 5° C. Other target temperatures may be used. Theheating temperature may be chosen using the Curie temperature of themagnetic material included in the magnet-containing portions, e.g., atemperature greater than the Curie temperature of the magnetic materialso that the magnetization of the magnets is lost.

A single batch of magnet-containing portions that the system heats atthe same time may include magnets of multiple formulations that havedifferent Curie temperatures. The heating temperature selected may beequal to or greater than the highest Curie temperature for any of themagnetic formulations to ensure that the magnetization of all thedifferent types of magnetic materials is removed.

In some implementations, the heating and cooling are both rapid. In someexamples, the temperature remains above the Curie temperature for apredefined minimum time in order to demagnetize the magnetic material.In some implementations, the magnet-containing portions are heated toabove the Curie temperature that is held for a predefined minimum time,and then the magnet-containing portions are cooled rapidly. Themagnet-containing portions may then be heated again and held for ashorter time and to a lower temperature and then rapidly cooled again.If demagnetization occurs in a first heating and cooling cycle, the sametemperature or hold time does not need to be achieved in later cyclesbut the cycling of hot and cold may be beneficial for removing themagnetic material from the adhesives and/or for fracturing the coating.In some implementations, the system heats the magnet-containing portionsat a rate of 10° C./sec or higher, preferably 50-100° C./sec. The systemmay rapidly cool the magnet-containing portions, for example, at a rateof 100° C./sec, preferably between about 200-1000° C./sec.

The process 500 may be performed on a batch of between about 50 to about1000 kg of the magnet-containing portions for about 1 hour in a furnaceto fully remove non-magnetic material from the magnetic material. Thegreater the mass of a batch loaded into a furnace, the longer theholding time in the furnace, e.g., because of convection. The holdingtime in the furnace may be a total time for all of the heating andcooling cycles, e.g., the furnace both heats and cools themagnet-containing portions.

An inert atmosphere may be employed in the furnace or the heating may beperformed in air. In some implementations, processing of the magneticmaterial once any coating is disrupted or removed from the magneticmaterial may employ inert atmosphere to protect the magnetic materialfrom excessive oxidation.

At S30, the entire coating is removed from the magnetic material. Thecoating may be removed by mechanical, chemical, and/or other methods. Insome examples, the coating is removed by shot blasting or abrasive jet.A chemical bath may follow the shot blasting or abrasive jet. Forexample, diluted hydrochloric, nitric acid, or other agent effective forremoving oxide may be used. The chemical bath may remove an oxide fromthe surface of the magnetic material.

At S40, the magnetic material, after mechanical and chemical treatment,is placed in a mixing apparatus. The mixing apparatus may subjects themagnetic material to a pressurized hydrogen atmosphere for apredetermined period of time, temperature, rotational speed, etc. Forinstance, the magnetic material may be processed by the hydrogen mixingreactor shown in FIG. 3B, FIG. 4G, or both or another appropriate mixingapparatus.

In some examples, rare earth transitional elemental additive materialmay be added to the magnetic material before or after mixing. In someimplementations, Nd—Fe—B magnets, e.g., waste magnet and rare earthelemental additive, for example, Nd_(1-x)Pr_(x), are placed together ina mixing apparatus at a ratio between 99.9:0.1 to 81:19 and arehomogeneously blended together. The rare earth transitional elementaladditive material may be fragmented separately and added to the wastemagnetic material after S40.

The rare earth transitional elemental additive material may be chosenusing an elemental analysis of the waste magnetic material compositionand a database of restoration formulas determined by experiment andextrapolation to be suitable for achieving a predefined targetformulation and magnetic performance or any other appropriate method.For instance, the database may include historical data indicatingcomposition properties of waste magnetic material and rare earthtransitional elemental additive material added to the starting materialto achieve desired properties for a resulting sintered recycled magnetproduct.

The magnetic and physical properties of the starting magnetic materialmay be restored or improved by the addition of certain rare earthtransitional elemental additive materials in a predefined proportionduring or after reduction of the starting magnetic material throughmixing e.g., hydride powder or crushed powder that is then processedinto a new sintered recycled magnet. An example of this formulation is99 parts waste Nd—Fe—B magnets and 1 part Pr, 25 wt. %, /Nd, 75 wt. %,elemental additive and in the case of 2:17-type magnets, which containSm₂Co₁₇, 1 part of Sm. Another example is 99 parts waste Nd—Fe—B magnetsand 1 part Nd, Dy, Co, Cu, and Fe elemental additive. In someimplementations, the combination is one of a waste rare earth magnet inmajor proportion in combination with a rare earth transitional elementaladditive or element in minor fraction. In some implementations, the rareearth transitional elemental additive is a combination of Nd and aLanthanide and another transitional metal. In some implementations, theelemental additive is less than 2% of the combination with the startingmagnetic material. In some implementations a Lanthanide may be replacedwith Pr.

At S50, the powder is fragmented and homogeneously mixed by suitablemeans. In some implementations, this is accomplished by jet milling to atarget particle size between about 1 to about 4 microns. The powder maybe fragmented, homogenized, or both using any appropriate fragmentationapparatus, such as those described in more detail above. In someimplementations, steps S40 and S50 may be performed concurrently. Insome implementations, instead of adding the rare earth transitionalelemental additive material minor fraction to the batch to behydrogenated, the rare earth material is separately hydrogenated andmixed in at S50. In some examples, the rare earth transitional elementaladditives may be milled separately and added after milling of thestarting waste magnetic material, e.g., after S50, during which thestarting waste magnetic material is preferably divided sufficiently toform a powder in the range of between about 1 to about 50 microns usinghigh pressure e.g., 60 bar.

At S60, larger particles, e.g., about 1 mm, are sieved out of thefragmented material, e.g., a powder oxidized fraction is processed bysieving out larger particles, such as particles between about 500microns to about 2 mm, from the fine powder. This procedure is effectivefor removing the oxidized fraction because of the hardness of oxidesrelative to the major fraction of recovered rare earth magnet materialwhich prevents the oxidized particles from fragmenting into smallerparts. For example, hydrogenation, milling, jet milling, crushing, oranother appropriate method, may be less apt to break up oxides leavingtheir size distribution larger and making possible to eliminate orreduce their proportion in the fine powder by sieving.

At S70, the fine powder is pressed and aligned to form a green compactby filling a press and establishing a magnetic field in the press, andat S80 the green compact is sintered and heat treated to form a recycledsintered magnet product.

FIG. 6 is a graph that shows an example of property ranges for startingmaterials which may be obtained as bulk and/or EOL magnets and forrecycled magnets. A bubble 302 drawn onto the graph represents theapproximate range of starting materials to which the process 500 canapply. The process 500 may also apply to other starting materialsoutside of the bubble 302.

FIG. 7 is a diagram comparing the composition of the original wastemagnetic material, shown in the left column, to the finished recycledmagnet product, shown in the right column, created by the process 500.In the starting magnetic material, the composition of rare earth metalsmay be greater or less than 18 at. %, noted by the “R” region of theleft column. An amount of rare earth metals “X” is removed from thestarting magnet material during processing. In order for the recycledNd—Fe—B product to have a composition similar to the original magnet,new rare earth material, i.e., virgin material, must be added.

In FIG. 7, the virgin material is represented by the “V” region and isapproximately equal to the amount of rare earth metals removed duringprocessing, or “X.” In the finished recycled product, the finalpercentage of rare earth metals is at least the percentage in thestarting magnetic material, but not higher than 18 at. %. If thepercentage of rare earth material in the starting magnetic material “R”is as low as the lower of the two dashed lines in the left column, e.g.,less than 18 at. %, the final rare earth atomic percentage in thefinished recycled magnet product, sown in the right column, is at leastequal to the same percentage, as depicted by the lower dashed linecarrying over. If, however, the percentage of rare earth metals in thestarting magnetic material is greater than 18 at. %, then the atomicpercentage in the finished recycled magnet is limited to 18%, as shownby the upper dashed line being capped at 18% in the right column.

In the finished recycled product, the final rare earth atomic percentageis one in which the percentage of each component, Nd, Pr, Dy, Gd, Tb,La, Ce, Yb, Ho, and/or Eu of virgin material is in the range of 0.1 to19% of its percentage in the original magnet, and the atomic percentageof Nd plus Pr is greater than zero.

Besides the rare earth metals, the remainder of both the startingmagnetic material and finished recycled magnets is composed of Fe, Co,Cu, aluminum, and other elements. In the finished recycled product, thefollowing limitations are present: (1) the atomic percentage of Co isnot more than 3%; (2) the atomic percentage of Cu is not more than 0.3%;and (3) the combined atomic percentage of Fe and Co is not more than77%.

FIG. 8 shows different shapes and coatings of sintered magnets 800. Anyof the sintered magnets 800 may be used during the recycling process500. Examples of the coatings of the sintered magnets 800 includephosphate 802, Al 804, NiCuNi 806, Epoxy 808, and Zn 810. For example,the abrasive jet cleaning device 60, shown in FIG. 3A, may remove thecoatings from the sintered magnets 800.

The following examples demonstrate that waste magnets from bulk and EOLsources of either uniform or mixed grade and performance, such asremanence (Br) and coercivity (iHc), may be aggregated and processed toform a new Nd—Fe—B recycled magnet with properties tailored to a desiredmagnetic performance, which is equal to or greater than the propertiesexhibited by the original starting magnetic material.

EXAMPLE 1

The waste magnets include a fractional mass composition determined byinductively coupled plasma (ICP) analysis and oxygen/carbon elementalanalyzer as indicated in Table 1A below. Using a permeameter, themagnetic properties, e.g., remanence, coercivity, etc., of the mixedwaste magnets were determined as indicated in Table 1B below. Tables 1Aand 1B characterize the waste magnetic material.

About 300 kilograms of mixed grade EOL magnets were held in a mufflefurnace and heated high above Curie temperature to 650° C. for 4 hoursto demagnetize the EOL magnets. The demagnetized magnets werecool-quenched in water to fracture the coating, and heated in a furnaceto 200° C. to dry. The demagnetized magnets were shot blasted for 15minutes for further removal of Ni—Cu—Ni coating and held in an inertatmosphere. Mass loss of the demagnetized magnets due to removal ofcoating was less than 5%. The uncoated magnets were chemically processedin diluted HCl.

A reaction rotating mixing vessel was loaded with 100 kg of the uncoatedimpurity-free waste material and 1% Nd(0.55x+1)Pr(0.45x+1) additive wasadded. The uncoated impurity-free waste material and the additives wereheld in the reaction rotating mixing vessel with 2 bar of hydrogenpressure for 4 hours at room temperature, e.g., about 20 to about 25° C.The resulting hydride mixture was then heated in situ to 550-600° C. topartially degas the hydride mixture. 1% Zn stearate was mixed withdegassed powder using a roller mill for 30 minutes to lubricate thedegassed powder. The degassed powder was jet milled for 1.5 hours underan Argon atmosphere for further homogenization until an average particlesize of approximately 2.5 μm or less was achieved. The resultingparticles were aligned and pressed, sintered, annealed and magnetized. Asintering temperature between about 1050° C. to about 1100° C. wasmaintained for 5 hours followed by heat treatment at 600° C. for 3hours.

ICP, elemental analysis, and permeameter testing was performed on thenew Nd—Fe—B sintered product. The compositions and magnetic propertiesof the new Nd—Fe—B sintered product are shown in Tables 2A and 2Brespectively.

In this example, an elemental composition of the rare earth elementaladditive RE, e.g., Nd/Pr, was prepared in situ with waste material toform a hydride powder blend. The RE additions substituted for theaccounted loss of rare earth oxides or grain boundary surface area phasethat was removed from the waste starting material, e.g., during stepsS20, S30, S40, S50 described with reference to FIG. 5. The partiallydegassed rare earth hydride additions may aid in solid state diffusionand/or reduce the amount of oxygen within the hydride powder duringsintering, where the crystal grain boundary phase, which is selectivelyenriched, is formed. In other words, the microstructure of the newlyformed magnet is modified compared to the starting material. Forinstance, the recycling process takes advantage of the restoration andimprovement of the grain boundary when the rare earth elemental additiveabsorbs the H₂ component of the process gas forming, e.g. NdPrH₃, whichis then transformed back to oxygen free NdPr during sintering.Therefore, the grain boundary restoration and reaction with the Nd₂Fe₁₄Bcomponent constitutes a newly formed microstructure and elementalcomposition so that the resulting Nd—Fe—B sintered magnet may exhibitproperties equal to or greater than the waste starting material,including Br, iHc, BHmax, or a combination of two or more of these.

In some examples, the rare earth RE additive component may be allowed todiffuse along the grain boundary by restoring and forming the grainboundary rich phase in the resulting Nd—Fe—B magnet with Nd-rich phasealone, and the coercive and remanent force is deteriorated, as describedin more detail with reference to Table 3B.

A rare earth proportion of the rare earth RE element from the wastemagnet may be replaced by fresh additions in the principal Nd₂Fe₁₄Bmatrix phase. In some implementations, the rare earth RE additives aresintered together with material from the waste magnets, allowing therare earth RE component to diffuse and penetrate selectively along thegrain boundary. Coercive force comparable to that of the original wastemagnet starting material may be recovered or improved in the recycledsintered magnet with the use of very small quantities of new rare earthmaterial. For example, a new recycled Nd—Fe—B product may bemanufactured which has superior properties when compared to the startingwaste materials.

Magnetic properties are reported in the Tables as BHmax (energyproduct), iHc (coercivity), and Br (remanence).

TABLE 1A Objective: ICP Analysis of magnetic material portion of EOLmagnets Sample Nd Pr Fe B Dy Al Co C O A-1 9.77 2.96 76.94 5.72 0.920.86 0.81 0.21 1.81 A-2 9.77 2.96 77.02 5.66 0.92 0.86 0.79 0.21 1.81B-1 9.65 2.95 74.95 5.56 0.90 0.84 0.78 2.63 1.74 B-2 9.64 2.94 74.965.56 0.90 0.84 0.79 2.63 1.74 C-1 9.59 2.95 77.35 5.67 1.06 0.98 0.860.21 1.33 C-2 9.54 2.94 76.69 5.69 1.05 0.97 0.68 1.12 1.32 D-1 9.623.01 77.15 5.73 1.06 0.98 0.75 0.21 1.49 D-2 9.61 2.96 77.13 5.72 1.060.98 0.84 0.21 1.49 E-1 10.89 3.44 75.06 5.76 0.54 1.85 0.12 0.43 1.91E-2 10.88 3.43 75.11 5.76 0.53 1.83 0.12 0.43 1.91

TABLE 1B Objective: Magnetic Properties of EOL magnets analyzed in Table1A Br iHc BHmax Density Sample (T) (kA/m) (kJ/m³) (g/cm³) A-1 1.22 1580280 7.54 B-1 1.23 1570 285 7.57 C-1 1.20 1680 270 7.52 D-1 1.20 1670 2707.54 E-1 1.22 1410 275 7.38

TABLE 2A Objective Mixed: ICP Analysis of recycled magnet SampleAdditive Nd Pr Fe B Dy Al Co C O A-1 1% Nd25 Pr75 10.74 3.26 75.62 5.810.91 0.80 0.75 0.60 1.51 A-2 1% Nd25 Pr75 10.74 3.26 75.62 5.81 0.910.82 0.73 0.60 1.51 A-3 1% Nd25 Pr75 10.72 3.25 75.32 5.79 0.90 0.800.79 0.60 1.83 A-4 1% Nd25 Pr75 10.72 3.25 75.35 5.79 0.90 0.80 0.760.60 1.83

TABLE 2B Objective Mixed: Magnetic Properties of recycled magnet Br iHcBHmax Density Sample Additive (T) (kA/m) (kJ/m³) (g/cm³) A-1 1% Nd25Pr75 1.23 1730 290 7.61 A-2 1% Nd25 Pr75 1.23 1730 290 7.61 A-3 1% Nd25Pr75 1.24 1720 290 7.61 A-4 1% Nd25 Pr75 1.25 1715 295 7.61

EXAMPLE 2

EOL magnet starting material was supplied in magnetized form. The EOLmagnets were initially attached to an Fe backing within EOL product. Themagnets were demagnetized and separated from the Fe backing using acyclic heating process described in more detail above. The recyclingsteps disclosed in Example 1 were used to process the mixed EOL magnetsand create new fully dense Nd—Fe—B sintered magnet product.

1% of additives, e.g., Nd_(x)/Pr_(y), were added to the waste magnet asindicated in the Additive column shown in tables 3A and 3C. The wastemagnets were characterized by ICP, elemental analysis, and permeameter.The compositions and magnetic properties of the starting waste materialand new Nd—Fe—B sintered product are shown in Tables 3A and 3Brespectively and tables 3C and 3D respectively.

Magnetic properties and corresponding densities are reported in theTables 3A to 5B as BHmax (energy product), iHc (coercivity), and Br(remanence).

TABLE 3A Objective: ICP Elemental Analysis, Starting Material andRecycled Magnets Sample Additive Nd Fe B Dy Al Pr C O Starting n/a 10.50Bal. 6.92 0.39 0.52 3.04 0.31 2.00 Material B-1 Nd pure 11.39 Bal. 6.850.39 0.52 3.01 0.31 1.98 B-2 Nd95 11.34 Bal. 6.85 0.39 0.52 3.06 0.311.98 Pr5 B-3 Nd90 11.29 Bal. 6.85 0.39 0.52 3.11 0.31 1.98 Pr10 B-4 Nd8511.23 Bal. 6.85 0.39 0.52 3.16 0.31 1.98 Pr15 B-5 Nd75 11.13 Bal. 6.850.39 0.52 3.26 0.31 1.98 Pr25 B-6 Nd50 10.89 Bal. 6.85 0.39 0.52 3.510.31 1.98 Pr50 B-7 Pr pure 10.40 Bal. 6.85 0.39 0.52 4.00 0.31 1.98

TABLE 3B Objective iHc: Magnetic Properties of Starting and RecycledMagnets Br iHc BH(max) Density Sample Additive (T) (kA/m) (kJ/m³)(g/cm³) Starting Material n/a 1.27 1160 310 7.45 B-1 Nd pure 1.23 1130290 7.50 B-2 Nd95Pr5 1.26 1200 305 7.53 B-3 Nd90Pr10 1.26 1230 305 7.53B-4 Nd85Pr15 1.26 1260 305 7.53 B-5 Nd75Pr25 1.26 1315 305 7.53 B-6Nd50Pr50 1.26 1335 305 7.53 B-7 Pr pure 1.25 1355 305 7.53

TABLE 3C Objective: ICP Elemental Analysis, Starting Material andRecycled Magnets Sample Additive Nd Fe B Dy Al Pr C O Starting n/a 10.50Bal. 6.92 0.39 0.52 3.04 0.31 2.00 Material B-8 1% 11.10 Bal. 6.85 0.390.52 3.26 0.31 1.98 Nd75 Pr25

TABLE 3D Objective iHc: Magnetic Properties of Starting and RecycledMagnets Br iHc BH(max) Density Sample Additive (T) (kA/m) (kJ/m³)(g/cm³) Starting Material n/a 1.26 1034 305 7.45 B-8 1% Nd75 Pr25 1.311034 331 7.56

EXAMPLE 3

The waste starting material magnets were characterized by ICP andpermeameter, see Tables 4A and 4B respectively. 0.5 to 8% of the Nd, Dy,Co, Cu and Fe additives were added to the waste magnet as indicated inthe Additive column of Tables 5A and 5B. The compositions and magneticproperties of the new Nd—Fe—B sintered product are shown in Tables 5Aand 5B respectively.

TABLE 4A Analysis of waste starting material Sam- ple Nd Fe B Dy Tb AlCu Co Pr GA C O A-1 10.15 Bal. 5.88 0.32 0.17 0.38 0.9 0.81 3.26 0.090.32 0.97

TABLE 4B Magnetic Properties of waste starting material Br iHc BH(max)Density Sample (T) (kA/m) (kJ/m³) (g/cm³) A-1 1.43 780 395 7.5

TABLE 5A Objective iHc: ICP Analysis of recycled magnets Sample AdditiveNd Fe B Dy Tb Al Cu Co Pr Ga C O C-1 0.5 at % 10.09 Bal. 5.88 0.42 0.170.38 0.10 0.90 3.18 0.07 0.32 1.00 NdDyCoCuFe C-2 1.0 at % 10.09 Bal.5.94 0.52 0.17 0.41 0.11 0.99 3.16 0.07 0.32 1.00 NdDyCoCuFe C-3 2.0 at% 10.10 Bal. 5.96 0.75 0.17 0.39 0.13 1.17 3.14 0.07 0.32 1.00NdDyCoCuFe C-4 3.0 at % 10.15 Bal. 5.92 0.94 0.17 0.41 0.17 1.37 3.150.07 0.31 1.10 NdDyCoCuFe C-5 5.0 at % 10.31 Bal. 5.99 1.38 0.17 0.390.25 1.68 3.19 0.07 0.33 1.10 NdDyCoCuFe C-6 8.0 at % 10.50 Bal. 6.072.05 0.18 0.40 0.35 2.35 3.23 0.07 0.32 1.10 NdDyCoCuFe

TABLE 5B Objective iHc: Magnetic Properties of Recycled Magnets Br iHcBH(max) Density Sample Additive (T) (kA/m) (kJ/m³) (g/cm³) C-1 0.5 at %NdDyCoCuFe 1.42 1050 395 7.6 C-2 1.0 at % NdDyCoCuFe 1.38 1200 370 7.6C-3 2.0 at % NdDyCoCuFe 1.33 1660 345 7.6 C-4 3.0 at % NdDyCoCuFe 1.291880 325 7.6 C-5 5.0 at % NdDyCoCuFe 1.24 2094 295 7.6 C-6 8.0 at %NdDyCoCuFe 1.16 2431 256 7.6

From Tables 2B and 3B, it can be observed that the Nd/Pr elementaladditives can be used to manipulate recovery of remanence and augmentthe coercivity for the resulting recycled sintered magnet. Specifically,the lower the purity of Nd in the elemental additives, greatercoercivity is recovered for the resulting recycled sintered magnet. Asmore Pr is added to the elemental additives—corresponding to a decreasein percentage of Nd present in the elemental additives—coercivityincreases, though remanence slightly decreases, for the resultingrecycled sintered magnet.

Similarly, coercivity and remanence of recycled sintered magnets can bemanipulated by altering the percentage of the Nd, Dy, Co, Cu and Feadditive, shown in Table 5B. For example, from Table 5B, it can beobserved that as the percentage of additive increases, corresponding toan increase in coercivity, remanence decreases. Thus, a low percentageof additive, such as 0.5% additive, may result in full restoration ofremanence, whereas a higher percentage of additive, such as 8% additive,may result in deterioration of remanence for the resulting recycledsintered magnet. With a higher percentage of additives there is at leastabout 30% to about 80% increase in coercive values, see Table 5B, whichmay be achieved for the new recycled sintered Nd—Fe—B product whencompared to waste starting martial in Table 4B.

The waste magnets that are recycled fit a range of possiblecompositions. For instance, the waste magnet compositions may include afirst magnet waste material of Fe of at least 72%, Nd in the range of7-20%, Pr of at least 2%, B of at least 5.6%, and Al of at least 0.1%.In some implementations, the first magnet waste material includes atleast one of Dy between 0 and 5%; Co between 0 and 4%; Cu between 0 and0.3%; Tb between 0 and 2.07%; Ga between 0 and 0.19%; Gd between 0 and1.25%; Ti between 0 and 0.14%; Zr between 0 and 0.3%; and Ni between 0and 0.3%. In some implementations, the first magnet waste materialincludes at least two of Dy between 0 and 5%; Co between 0 and 4%; Cubetween 0 and 0.3%; Tb between 0 and 2.07%; Ga between 0 and 0.19%; Gdbetween 0 and 1.25%; Ti between 0 and 0.14%; Zr between 0 and 0.3%; andNi between 0 and 0.3%. In some implementations, the first magnet wastematerial includes at least three of Dy between 0 and 5%; Co between 0and 4%; Cu between 0 and 0.3%; Tb between 0 and 2.07%; Ga between 0 and0.19%; Gd between 0 and 1.25%; Ti between 0 and 0.14%; Zr between 0 and0.3%; and Ni between 0 and 0.3%.

In some implementations, the first magnet waste material includes atleast four of Dy between 0 and 5%; Co between 0 and 4%; Cu between 0 and0.3%; Tb between 0 and 2.07%; Ga between 0 and 0.19%; Gd between 0 and1.25%; Ti between 0 and 0.14%; Zr between 0 and 0.3%; and Ni between 0and 0.3%. In some implementations, the first magnet waste materialincludes at least five of Dy between 0 and 5%; Co between 0 and 4%; Cubetween 0 and 0.3%; Tb between 0 and 2.07%; Ga between 0 and 0.19%; Gdbetween 0 and 1.25%; Ti between 0 and 0.14%; Zr between 0 and 0.3%; andNi between 0 and 0.3%. In some implementations, the first magnet wastematerial includes at least six of Dy between 0 and 5%; Co between 0 and4%; Cu between 0 and 0.3%; Tb between 0 and 2.07%; Ga between 0 and0.19%; Gd between 0 and 1.25%; Ti between 0 and 0.14%; Zr between 0 and0.3%; and Ni between 0 and 0.3%.

In some implementations, the first magnet waste material includes atleast seven of Dy between 0 and 5%; Co between 0 and 4%; Cu between 0and 0.3%; Tb between 0 and 2.07%; Ga between 0 and 0.19%; Gd between 0and 1.25%; Ti between 0 and 0.14%; Zr between 0 and 0.3%; and Ni between0 and 0.3%. In some implementations, the first magnet waste materialincludes at least eight of Dy between 0 and 5%; Co between 0 and 4%; Cubetween 0 and 0.3%; Tb between 0 and 2.07%; Ga between 0 and 0.19%; Gdbetween 0 and 1.25%; Ti between 0 and 0.14%; Zr between 0 and 0.3%; andNi between 0 and 0.3%. In some implementations, the first magnet wastematerial includes at least nine of Dy between 0 and 5%; Co between 0 and4%; Cu between 0 and 0.3%; Tb between 0 and 2.07%; Ga between 0 and0.19%; Gd between 0 and 1.25%; Ti between 0 and 0.14%; Zr between 0 and0.3%; and Ni between 0 and 0.3%.

In some implementations, some of the above implementations include atleast one of Dy between 0 and 5%; Co between 0 and 4%; Cu between 0 and0.3%; Tb between 0 and 2.07%; Ga between 0 and 0.19%; Gd between 0 and1.25%; Ti between 0 and 0.14%; Zr between 0 and 0.3%; and Ni between 0and 0.3%. In some implementations, some of the above implementationsinclude at least one of Dy between 0 and 5%; Co between 0 and 4%; Cubetween 0 and 0.3%; Tb between 0 and 2.07%; Ga between 0 and 0.19%; Gdbetween 0 and 1.25%; Ti between 0 and 0.14%; Zr between 0 and 0.3%; andNi between 0 and 0.3%.

In some implementations, the magnet waste material includes at least oneof Dy between 0.1 and 5%; Co between 0.1 and 4%; Cu between 0.1 and0.3%; Tb between 0.1 and 2.07%; Ga between 0.01 and 0.19%; Gd between0.01 and 1.25%; Ti between 0.01 and 0.14%; Zr between 0.01 and 0.3%; andNi between 0.01 and 0.3%. In some implementations, the magnet wastematerial includes at least two of Dy between 0.1 and 5%; Co between 0.1and 4%; Cu between 0.1 and 0.3%; Tb between 0.1 and 2.07%; Ga between0.01 and 0.19%; Gd between 0.01 and 1.25%; Ti between 0.01 and 0.14%; Zrbetween 0.01 and 0.3%; and Ni between 0.01 and 0.3%. In someimplementations, the magnet waste material includes at least three of Dybetween 0.1 and 5%; Co between 0.1 and 4%; Cu between 0.1 and 0.3%; Tbbetween 0.1 and 2.07%; Ga between 0.01 and 0.19%; Gd between 0.01 and1.25%; Ti between 0.01 and 0.14%; Zr between 0.01 and 0.3%; and Nibetween 0.01 and 0.3%.

In some implementations, the magnet waste material includes at leastfour of Dy between 0.1 and 5%; Co between 0.1 and 4%; Cu between 0.1 and0.3%; Tb between 0.1 and 2.07%; Ga between 0.01 and 0.19%; Gd between0.01 and 1.25%; Ti between 0.01 and 0.14%; Zr between 0.01 and 0.3%; andNi between 0.01 and 0.3%. In some implementations, the magnet wastematerial includes at least five of Dy between 0.1 and 5%; Co between 0.1and 4%; Cu between 0.1 and 0.3%; Tb between 0.1 and 2.07%; Ga between0.01 and 0.19%; Gd between 0.01 and 1.25%; Ti between 0.01 and 0.14%; Zrbetween 0.01 and 0.3%; and Ni between 0.01 and 0.3%. In someimplementations, the magnet waste material includes at least six of Dybetween 0.1 and 5%; Co between 0.1 and 4%; Cu between 0.1 and 0.3%; Tbbetween 0.1 and 2.07%; Ga between 0.01 and 0.19%; Gd between 0.01 and1.25%; Ti between 0.01 and 0.14%; Zr between 0.01 and 0.3%; and Nibetween 0.01 and 0.3%.

In some implementations, the magnet waste material includes at leastseven of Dy between 0.1 and 5%; Co between 0.1 and 4%; Cu between 0.1and 0.3%; Tb between 0.1 and 2.07%; Ga between 0.01 and 0.19%; Gdbetween 0.01 and 1.25%; Ti between 0.01 and 0.14%; Zr between 0.01 and0.3%; and Ni between 0.01 and 0.3%. In some implementations, the magnetwaste material includes at least eight of Dy between 0.1 and 5%; Cobetween 0.1 and 4%; Cu between 0.1 and 0.3%; Tb between 0.1 and 2.07%;Ga between 0.01 and 0.19%; Gd between 0.01 and 1.25%; Ti between 0.01and 0.14%; Zr between 0.01 and 0.3%; and Ni between 0.01 and 0.3%. Insome implementations, the magnet waste material includes at least nineof Dy between 0.1 and 5%; Co between 0.1 and 4%; Cu between 0.1 and0.3%; Tb between 0.1 and 2.07%; Ga between 0.01 and 0.19%; Gd between0.01 and 1.25%; Ti between 0.01 and 0.14%; Zr between 0.01 and 0.3%; andNi between 0.01 and 0.3%.

In some implementations, the waste magnet composition described hereincontains trace amounts of one or more of Dy, Co, Cu, Tb, Ga, Gd, Ti, Zr,Ni or combinations thereof. In some implementations, the waste magnetcomposition described herein contains impurities of one or more of Dy,Co, Cu, Tb, Ga, Gd, Ti, Zr, Ni or combinations thereof. In someimplementations, the waste magnet composition described herein containsless than about 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, or 1% of one or more ofDy, Co, Cu, Tb, Ga, Gd, Ti, Zr, Ni or combinations thereof. In someimplementations, the waste magnet compositions described herein do notcontain one or more of Dy, Co, Cu, Tb, Ga, Gd, Ti, Zr, Ni orcombinations thereof. In some implementations, the waste magnetcompositions described herein comprise, consist essentially of, orconsist of any of the ranges provided herein.

Table 6 shows combinations of materials that define other possiblerecycled magnet materials according to some implementations.

TABLE 6 Recycled magnet composition envelope Component At least % Notmore than % Fe 72 83 Nd 7 25 Pr 2 4 B 5.6 6.4 Al 0.1 2.9 Dy 0 5 Co 0 4Cu 0 0.3 Tb 0 2.07 Ga 0 0.19 Gd 0 1.25 Ti 0 0.14 Zr 0 0.3 Ni 0 0.3

In some implementations, waste magnet material, whose composition rangesare defined in the tables above, may be combined with an amount of arare earth elemental additive, before, during or after mixing to producean optimum magnetic powder mixture, with about 0.5 to about 8 at % ofthe magnetic powder from the rare earth elemental additive. In someimplementations, the amount of elemental additives is such that at leastone of the elemental components of the rare earth elemental additives isat least the same amount of the same element that is lost from the wastemagnet starting material during the initial processing steps. In someimplementations, the amount of elemental additives is such that at leastone of the elemental components of the rare earth elemental additives isequal to an amount of the same element that is lost from the wastemagnet starting material during the initial processing steps and furtherprocessing steps. To determine the amount of lost material, a sample ofwaste magnet starting material can be processed and analyzed using ICPto determine the change in rare earth elemental constituents. Forexample, the reduction in concentration of elemental Nd may be 0.7%. Inthis case, a 1% added Nd(0.70)Pr(0.25)(0.05 other materials) elementaladditive would be effective to restore the original grain boundary richphase in the recovered Nd—Fe—B sintered magnet product. In someexamples, when a reduction in the concentration of Nd is 0.7%, twice theelemental additive may be added, e.g., 2%, such that the total amount ofNd, Pr, and Dy does not exceed 18% in the resulting Nd—Fe—B sinteredproduct.

The following formulas further describe some implementations:R=s(Nd)+s(Pr)+s(Dy) in waste magnet starting material;T=f(Nd)+f(Pr)+f(Dy) in final Nd—Fe—B product, as defined in paragraph19; and virgin material added V=Nd[p]+Pr[q]+Dy[r], where 0.1≦p+q+r≦19at. % of final product and T≧min(R, 18 at. %). For illustrativepurposes, consider the following example: If the atomic percentagevalues for Nd, Pr, and Dy in an waste magnet starting material are 9.77,2.96, and 0.92, respectively, then substituting the corresponding valuesinto the formula R=s(Nd)+s(Pr)+s(Dy) yields R=9.77+2.96+0.92, orR=13.65. In the same example, the atomic percentage values for Nd, Pr,and Dy in the new recycled Nd—Fe—B sintered magnet might be 10.74, 3.26,and 0.91, respectively. Upon substituting the values of the new recycledNd—Fe—B sintered magnet into the formula T=s(Nd)+s(Pr)+s(Dy), T thenequals 10.74+3.26+0.91, or T=14.91. If, in the same example, virginmaterial is added during the recycling process, and the virgin materialcontains atomic percentage values of 0.2, 0.3, and 0.4 for Nd, Pr, andDy, respectively, the formula V=Nd[p]+Pr[q]+Dy[r] yields V=0.2+0.3+0.4,or V=0.9. The formula for the virgin material, or V, is subject to twoconstraints: 0.1≦p+q+r≦19% of final product and T≧min(R, 18 at. %). Inour example, p+q+r=0.9%, which satisfies the first constraint—that thevalue of p+q+r must be greater than or equal to 0.1% and less than orequal to 19%. This example also satisfies the second constraint for theformula for the virgin material: T is greater than or equal to theminimum of the set of R or 18. In this example, T is 14.91 and theminimum of the set of R or 18 is R, which is 13.65, so T is greater thanor equal to the minimum of the set of R or 18.

In some implementations, V=Nd[p]+Pr[q]+Dy[r], where 0.1≦p+q+r≦15 at. %of final product and T≧min(R, 18 at. %). In some implementations,V=Nd[p]+Pr[q]+Dy[r], where 0.1≦p+q+r≦12 at. % of final product andT≧min(R, 18 at. %). In some implementations, V=Nd[p]+Pr[q]+Dy[r], where0.1≦p+q+r≦8 at. % of final product and T≧min(R, 18 at. %). In someimplementations, V=Nd[p]+Pr[q]+Dy[r], where 0.1≦p+q+r≦Sat. % of finalproduct and T≧min(R, 18 at. %). In some implementations,V=Nd[p]+Pr[q]+Dy[r], where 0.1≦p+q+r≦3 at. % of final product andT≧min(R, 18 at. %). In some implementations, V=Nd[p]+Pr[q]+Dy[r], where0.1≦p+q+r≦2 at. % of final product and T≧min(R, 18 at. %). In someimplementations, V=Nd[p]+Pr[q]+Dy[r], where 0.1≦p+q+r≦lat. % of finalproduct and T≧min(R, 18 at. %).

In some implementations, X is at. % RE (Nd, Pr, Dy) removed fromoriginal magnet, and p+q+r≧X. In some implementations, the additive issuch that in the final recycled Nd—Fe—B sintered product, where f is afraction by at % of recycled Nd—Fe—B sintered, f(Nd)+f(Pr)>0. In someimplementations, f(Nd)+f(Pr)+f(Dy)≦18. In some implementations, f(Co)≦3.In some implementations, f(Cu)≦0.3. In some implementations,f(Fe)+f(Co)≦77. In some implementations, f(Dy)+f(Nd)+f(Pr)≧R.

In some implementations, the elemental additions are Nd[0.1-19 at.%*s(Nd), x]Pr[0.1-19 at. %*s(Pr), y]Dy[0.1-19%*s(Dy), z]Co[0, d]Cu[0,e]Fe[0, f], where [m,n] means a range from minimum m and maximum n; s(t)is the atomic percent of element t in starting composition; f(t) is theatomic percent of element t in final composition; x=18−[81, 99.9] at.%*(s(Nd)+s(Pr)+s(Dy)); y=18−[81, 99.9] at. %*(s(Nd)+s(Pr)+s(Dy));z=18−[81, 99.9] at. %*(s(Nd)+s(Pr)+s(Dy)); d=3−[81, 99.9] at. %*s(Co);e=0.3−[81, 99.9] at. %* s(Cu); f=77−[81, 99.9] at. %*(s(Fe)+s(Co)).

In some implementations, (i) virgin material, e.g., Nd_(p)Pr_(q)Dy_(r),need be in the range of 0.1≦p+q+r≦19 at. % of final product, andT≧min(R, 18), where T=f(Nd)+f(Pr)+f(Dy) and R=s(Nd)+s(Pr)+s(Dy); (ii)p+q+r≧X, where X is at. % RE (Nd, Pr, Dy) removed from original magnet;(iii) T≦18%; (iv) f(Nd)+f(Pr)>0, where f is an at. % fraction of thefinal product; (v) f(Nd)+f(Pr)+f(Dy)<=18; (vi) f(Co)<=3; (vii)f(Cu)<=0.3; (viii) f(Fe)+f(Co)<=77; and (ix) f(Dy)+f(Nd)+f(Pr)>=R.

In some implementations, a method provides for the addition of 0.1 to 19wt. % of one or more rare earth elemental additives to a composition ormethod described herein. In another aspect, a method provides for theaddition of about 0.1 wt. %, about 0.2 wt. %, about 0.3 wt. %, about 0.4wt. %, about 0.5 wt. %, about 1 wt. %, about 2 wt. %, about 3 wt. %,about 4 wt. %, about 5 wt. %, about 6 wt. %, about 7 wt. %, about 8 wt.%, about 9 wt. %, about 10 wt. %, about 11 wt. %, about 12 wt. %, about13 wt. %, about 14 wt. %, about 15 wt. %, about 16 wt. %, about 17 wt.%, about 18 wt. %, or about 19 wt. % of one or more elemental additionsor a combination of one or more elemental additions to a composition ormethod described herein. In yet another aspect, a method provides forthe addition of about 0.1-0.5 wt. %, about 0.1-1 wt. %, about 0.5-1 wt.%, about 1-2 wt. %, about 1-3 wt. %, about 1-5 wt. %, about 1-8 wt. %,about 1-12 wt. %, bout 1-15 wt. %, about 1-19 wt. % about 2-4 wt. %,about 2-6 wt. %, about 2-12 wt. %, about 2-19 wt. %, about 3-5 wt. %,about 3-8 wt. %, about 3-15 wt. %, and about 3-19 wt. % of one or moreelemental additions or a combination of one or more elemental additionsto a composition or method described herein.

In some implementations, inevitable impurities may be combined with theidentified materials.

Embodiments of the subject matter and the functional operationsdescribed in this specification can be implemented in digital electroniccircuitry, in tangibly-embodied computer software or firmware, incomputer hardware, including the structures disclosed in thisspecification and their structural equivalents, or in combinations ofone or more of them. Embodiments of the subject matter described in thisspecification can be implemented as one or more computer programs, i.e.,one or more modules of computer program instructions encoded on atangible non transitory program carrier for execution by, or to controlthe operation of, data processing apparatus. Alternatively or inaddition, the program instructions can be encoded on an artificiallygenerated propagated signal, e.g., a machine-generated electrical,optical, or electromagnetic signal, that is generated to encodeinformation for transmission to suitable receiver apparatus forexecution by a data processing apparatus. The computer storage mediumcan be a machine-readable storage device, a machine-readable storagesubstrate, a random or serial access memory device, or a combination ofone or more of them.

The term “data processing apparatus” refers to data processing hardwareand encompasses all kinds of apparatuses, devices, and machines forprocessing data, including by way of example a programmable processor, acomputer, or multiple processors or computers. The apparatus can alsobe, or further include, special purpose logic circuitry, e.g., an FPGA(field programmable gate array) or an ASIC (application specificintegrated circuit). The apparatus can optionally include, in additionto hardware, code that creates an execution environment for computerprograms, e.g., code that constitutes processor firmware, a protocolstack, a database management system, an operating system, or acombination of one or more of them.

A computer program, which may also be referred to or described as aprogram, software, a software application, a module, a software module,a script, or code, can be written in any form of programming language,including compiled or interpreted languages, or declarative orprocedural languages, and it can be deployed in any form, including as astand alone program or as a module, component, subroutine, or other unitsuitable for use in a computing environment. A computer program may, butneed not, correspond to a file in a file system. A program can be storedin a portion of a file that holds other programs or data, e.g., one ormore scripts stored in a markup language document, in a single filededicated to the program in question, or in multiple coordinated files,e.g., files that store one or more modules, sub programs, or portions ofcode. A computer program can be deployed to be executed on one computeror on multiple computers that are located at one site or distributedacross multiple sites and interconnected by a communication network.

The processes and logic flows described in this specification can beperformed by one or more programmable computers executing one or morecomputer programs to perform functions by operating on input data andgenerating output. The processes and logic flows can also be performedby, and apparatus can also be implemented as, special purpose logiccircuitry, e.g., an FPGA (field programmable gate array) or an ASIC(application specific integrated circuit).

Computers suitable for the execution of a computer program include, byway of example, general or special purpose microprocessors or both, orany other kind of central processing unit. Generally, a centralprocessing unit will receive instructions and data from a read onlymemory or a random access memory or both. The essential elements of acomputer are a central processing unit for performing or executinginstructions and one or more memory devices for storing instructions anddata. Generally, a computer will also include, or be operatively coupledto receive data from or transfer data to, or both, one or more massstorage devices for storing data, e.g., magnetic, magneto optical disks,or optical disks. However, a computer need not have such devices.Moreover, a computer can be embedded in another device, e.g., a mobiletelephone, a personal digital assistant (PDA), a mobile audio or videoplayer, a game console, a Global Positioning System (GPS) receiver, or aportable storage device, e.g., a universal serial bus (USB) flash drive,to name just a few.

Computer readable media suitable for storing computer programinstructions and data include all forms of non volatile memory, mediaand memory devices, including by way of example semiconductor memorydevices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks,e.g., internal hard disks or removable disks; magneto optical disks; andCD ROM and DVD-ROM disks. The processor and the memory can besupplemented by, or incorporated in, special purpose logic circuitry.

To provide for interaction with a user, embodiments of the subjectmatter described in this specification can be implemented on a computerhaving a display device, e.g., a CRT (cathode ray tube) or LCD (liquidcrystal display) monitor, for displaying information to the user and akeyboard and a pointing device, e.g., a mouse or a trackball, by whichthe user can provide input to the computer. Other kinds of devices canbe used to provide for interaction with a user as well; for example,feedback provided to the user can be any form of sensory feedback, e.g.,visual feedback, auditory feedback, or tactile feedback; and input fromthe user can be received in any form, including acoustic, speech, ortactile input. In addition, a computer can interact with a user bysending documents to and receiving documents from a device that is usedby the user; for example, by sending web pages to a web browser on auser's device in response to requests received from the web browser.

Embodiments of the subject matter described in this specification can beimplemented in a computing system that includes a back end component,e.g., as a data server, or that includes a middleware component, e.g.,an application server, or that includes a front end component, e.g., aclient computer having a graphical user interface or a Web browserthrough which a user can interact with an implementation of the subjectmatter described in this specification, or any combination of one ormore such back end, middleware, or front end components. The componentsof the system can be interconnected by any form or medium of digitaldata communication, e.g., a communication network. Examples ofcommunication networks include a local area network (LAN) and a widearea network (WAN), e.g., the Internet.

The computing system can include clients and servers. A client andserver are generally remote from each other and typically interactthrough a communication network. The relationship of client and serverarises by virtue of computer programs running on the respectivecomputers and having a client-server relationship to each other. In someembodiments, a server transmits data, e.g., an HTML page, to a userdevice, e.g., for purposes of displaying data to and receiving userinput from a user interacting with the user device, which acts as aclient. Data generated at the user device, e.g., a result of the userinteraction, can be received from the user device at the server.

An example of one such type of computer is shown in FIG. 9, which showsa schematic diagram of a generic computer system 900. The system 900 canbe used for the operations described in association with any of thecomputer-implement methods described previously, according to oneimplementation. The system 900 includes a processor 910, a memory 920, astorage device 930, and an input/output device 940. Each of thecomponents 910, 920, 930, and 940 are interconnected using a system bus950. The processor 910 is capable of processing instructions forexecution within the system 900. In one implementation, the processor910 is a single-threaded processor. In another implementation, theprocessor 910 is a multi-threaded processor. The processor 910 iscapable of processing instructions stored in the memory 920 or on thestorage device 930 to display graphical information for a user interfaceon the input/output device 940.

The memory 920 stores information within the system 900. In oneimplementation, the memory 920 is a computer-readable medium. In oneimplementation, the memory 920 is a volatile memory unit. In anotherimplementation, the memory 920 is a non-volatile memory unit.

The storage device 930 is capable of providing mass storage for thesystem 900. In one implementation, the storage device 930 is acomputer-readable medium. In various different implementations, thestorage device 930 may be a floppy disk device, a hard disk device, anoptical disk device, or a tape device.

The input/output device 940 provides input/output operations for thesystem 900. In one implementation, the input/output device 940 includesa keyboard and/or pointing device. In another implementation, theinput/output device 940 includes a display unit for displaying graphicaluser interfaces.

While this specification contains many specific implementation details,these should not be construed as limitations on the scope of anyinvention or on the scope of what may be claimed, but rather asdescriptions of features that may be specific to particular embodimentsof particular inventions. Certain features that are described in thisspecification in the context of separate embodiments can also beimplemented in combination in a single embodiment. Conversely, variousfeatures that are described in the context of a single embodiment canalso be implemented in multiple embodiments separately or in anysuitable subcombination. Moreover, although features may be describedabove as acting in certain combinations and even initially claimed assuch, one or more features from a claimed combination can in some casesbe excised from the combination, and the claimed combination may bedirected to a subcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and parallel processingmay be advantageous. Moreover, the separation of various system modulesand components in the embodiments described above should not beunderstood as requiring such separation in all embodiments, and itshould be understood that the described program components and systemscan generally be integrated together in a single software product orpackaged into multiple software products.

Particular embodiments of the subject matter have been described. Otherembodiments are within the scope of the following claims. For example,the actions recited in the claims can be performed in a different orderand still achieve desirable results. As one example, the processesdepicted in the accompanying figures do not necessarily require theparticular order shown, or sequential order, to achieve desirableresults. In some cases, multitasking and parallel processing may beadvantageous.

What is claimed is:
 1. A method for manufacturing a recycled Nd—Fe—Bpermanent magnet comprising: demagnetizing magnetic material from awaste magnet assembly by cyclic heating And cooling of the magneticmaterial, fragmenting adhesives attached to the magnetic material,cracking coating layers of the magnetic material, and subjecting themagnetic material to at least one of: a) a mechanical treatment or b) achemical treatment, to remove the coating layers and prepare themagnetic material without impurities; fragmenting the demagnetizedmagnetic material to form a powder; mixing the powder with a) a rareearth material R that comprises between 0.1 to 1 at. % of the totalmixture and b) an elemental additive A to produce a homogeneous powder,wherein the rare earth material R comprises at least one of: i) Nd orii) Pr with a ratio of 75 wt. % Nd to 25 wt. % Pr, and the elementaladditive A comprises at least one of: i) Dy, ii) Co, iii) Cu, iv) Fe;and sintering and magnetizing the homogenous powder to form a recycledNd—Fe—B magnetic product that comprises 1.98 at. % oxygen or less andhas a remanence and a coercivity at least the same as a waste magnetpart from the waste magnet assembly.
 2. The method of claim 1 comprisingperforming the fragmenting and the mixing concurrently.
 3. The method ofclaim 1 wherein fragmenting the demagnetized magnetic material comprisesfragmenting the demagnetized magnetic material to an average particlesize between 1 to 4 microns.
 4. The method of claim 1 whereinfragmenting the demagnetized magnetic material to form the powdercomprises removing particles with a particle fraction size bigger thanan average size of particles in the demagnetized magnetic material fromthe demagnetized magnetic material to obtain 1.98 at. % oxygen or lessin the demagnetized magnetic material.
 5. The method of claim 4 whereinremoving, from the demagnetized magnetic material, particles with theparticle fraction size bigger than the average size of particles in thedemagnetized magnetic material to obtain 1.98 at. % oxygen or less inthe demagnetized magnetic material comprises removing particles in aninert atmosphere.
 6. The method of claim 5, wherein removing particlesin an inert atmosphere comprises removing particles in argon.
 7. Themethod of claim 4 wherein removing, from the demagnetized magneticmaterial, particles with the particle fraction size bigger than theaverage size of particles in the demagnetized magnetic material toobtain 1.98 at. % oxygen or less in the demagnetized magnetic materialcomprises sieving.
 8. The method of claim 1 comprising: mixing thehomogenous powder with another element selected from the elementaladditive A.
 9. The method of claim 1 comprising: harvesting the magneticmaterial from one or more magnet assemblies by: separating a wastemagnet part from a non-magnet part included in the magnet assemblies;and extracting the waste magnet part from the non-magnet part, whereinthe magnetic material comprises the waste magnet part.
 10. The method ofclaim 1 wherein fragmenting the demagnetized magnetic material to formthe powder comprises fragmenting the demagnetized magnetic material toform the powder with an average particle size between about 1 micron toabout 2 millimeters, the method comprising: further fragmenting thepowder to an average particle size between about 1 to about 4 microns;and homogenizing the powder.
 11. The method of claim 10 wherein:homogenizing the powder comprises homogenizing the powder that comprisesan average particle size between about 1 micro to about 2 millimeters;and mixing the powder with a) the rare earth material R that comprisesbetween 0.1 to 1 at. % of the total mixture and b) the elementaladditive A to produce the homogeneous powder comprises mixing the powderwith an average particle size between about 1 to about 4 micros with a)the rare earth material R and b) the elemental additive A to produce thehomogenous powder.
 12. The method of claim 10 wherein: mixing the powderwith a) the rare earth material R that comprises between 0.1 to 1 at. %of the total mixture and b) the elemental additive A to produce thehomogeneous powder comprises mixing the powder with an average particlesize between about 1 micron to about 2 millimeters with a) the rareearth material R and b) the elemental additive A to produce thehomogenous powder; and homogenizing the powder comprises homogenizingthe powder that comprises an average particle size between about 1 toabout 4 microns.
 13. The method of claim 1 comprising: fragmenting therare earth material R and the elemental additive A separately fromfragmenting the demagnetized magnetic material to form the powder,wherein mixing the powder with a) the rare earth material R thatcomprises between 0.1 to 1 at. % of the total mixture and b) theelemental additive A to produce the homogeneous powder comprises mixingthe powder with a) the fragmented rare earth material R and b) thefragmented elemental additive A to produce the homogeneous powder. 14.The method of claim 1 where sintering and magnetizing the homogenouspowder to form a recycled Nd—Fe—B magnetic product comprises: adding alubricant to the homogenous powder; compacting the homogenous powder toform a green compact; sintering the green compact between about 1000° C.to about 1100° C.; heat treating the sintered green compact betweenabout 490° C. to about 950° C.; and magnetizing the heat treated greencompact to an inert atmosphere below 15° C. to form the recycled Nd—Fe—Bmagnetic product.
 15. The method of claim 1, wherein an atomicpercentage of Co in the recycled Nd—Fe—B magnetic product is less thanor equal to 3 at. %.
 16. The method of claim 1, wherein an atomicpercentage of Cu in the recycled Nd—Fe—B magnetic product is less thanor equal to 0.3 at. %.
 17. The method of claim 1, wherein a combinedatomic percentage of Fe and Co in the recycled Nd—Fe—B magnetic productis less than or equal to 77 at. %.
 18. The method of claim 1, wherein acombined atomic percentage of Nd, Pr, and Dy in the recycled Nd—Fe—Bmagnetic product is greater than or equal to a combined atomicpercentage of Nd, Pr, and Dy in a waste magnet part from the wastemagnet assembly.
 19. The method of claim 1, wherein a combined atomicpercentage of Nd, Dy, and Pr in the recycled Nd—Fe—B magnetic product isless than or equal to 18 at. %.
 20. The method of claim 1, wherein thecoercivity of the recycled Nd—Fe—B magnetic product is between about 0to about 20% greater than the coercivity of a waste magnet part from thewaste magnet assembly.
 21. The method of claim 1, wherein: mixing thepowder with a) the rare earth material R that comprises between 0.1 to 1at. % of the total mixture and b) the elemental additive A to producethe homogeneous powder comprises homogeneously distributing the rareearth material R and the elemental additive A within the demagnetizedmagnetic material; and sintering and magnetizing the homogenous powderto form the recycled Nd—Fe—B magnetic product comprises forming therecycled Nd—Fe—B magnetic product having a composition substantially ofW_(a)R_(b)A_(c) with a concentration of the rare earth material R and aconcentration of the elemental additive A that increases, on average,surrounding a primary Nd₂Fe₁₄B phase within the recycled Nd—Fe—Bmagnetic product, where W comprises Nd—Fe—B material from the wastemagnetic assembly and indices a, b, and c comprise atomic percentages ofthe corresponding compositions or elements.
 22. The method of claim 21wherein forming the recycled Nd—Fe—B magnetic product comprisesmodifying an elemental concentration and an elemental composition of agrain boundary phase, on average, at a plurality of grain boundaryregions that extend throughout the recycled Nd—Fe—B magnetic product by:forming NdPrH₃ from H₂ processing gas and the rare earth material R; andduring sintering, transforming the NdPrH₃ to oxygen free NdPr.
 23. Themethod of claim 1, wherein: sintering and magnetizing the homogenouspowder to form the recycled Nd—Fe—B magnetic product comprises sinteringand magnetizing the homogenous powder to form the recycled Nd—Fe—Bmagnetic product having a composition substantially of W_(a)R_(b)A_(c),where W comprises Nd—Fe—B material from the waste magnetic assembly;indices a, b, and c comprise atomic percentages of the correspondingcompositions or elements; a(t) is the atomic percent of element t in thewaste material W; b(t) is the atomic percent of element t in the rareearth containing material R; c(t) is the atomic percent of element t inthe elemental additives A; and a, b, c, a(t), b(t), and c(t) have valuessatisfying: 81 at. %≦a ≦99.9 at. %, 0.1 at. %≦b ≦1 at. %, 3 at. %−99.9at. %*a(Co)≦c(Co)≦3 at. %−81 at. %*a(Co), 0.3 at. %−99.9 at.%*a(Cu)≦c(Cu)≦0.3 at. %−81 at. %*a(Cu), 77 at. %−99.9 at.%*(a(Fe)+a(Co))≦c(Fe)≦77 at. %−81 at. %*(a(Fe)+a(Co)),a(Nd)+b(Nd)+a(Pr)+b(Pr)>0 at. %,a(Nd)+b(Nd)+a(Pr)+b(Pr)+a(Dy)+b(Dy)+c(Dy)≦18 at. %, a(Co)+b(Co)+c(Co)≦3at. %, a(Cu)+b(Cu)+c(Cu)≦0.3 at. %,a(Fe)+b(Fe)+c(Fe)+a(Co)+b(Co)+c(Co)≦77 at. %, andb(Nd)+b(Pr)+b(Dy)+c(Dy)≧0 at. %.
 24. The method of claim 1, whereinsintering and magnetizing the homogenous powder to form the recycledNd—Fe—B magnetic product comprises sintering and magnetizing thehomogenous powder to form the recycled Nd—Fe—B magnetic product having acomposition substantially of W_(a)R_(b)A_(c), where W comprises Nd—Fe—Bmaterial from the waste magnetic assembly and indices a, b, and ccomprise atomic percentages of the corresponding compositions orelements and the rare earth material R and the elemental additive Asatisfy:Nd[0.1−1 at. %*s(Nd), x],Pr[0.1−1 at. %*s(Pr), y],Dy[0.1−19 at. %*s(Dy), z],Co[0 at. %, d],Cu[0 at. %, e],Fe[0 at. %, f], wherein: [m, n] means a range from a first value in aminimum interval m and a second value in a maximum interval n; s(t) isthe atomic percent of element t in starting composition; x =18 at.%−[99, 99.9] at. % *(s(Nd)+s(Pr)+s(Dy)); y=18 at. %−[99, 99.9] at. %*(s(Nd)+s(Pr)+s(Dy)); z=18 at. %−[81, 99.9] at. %*(s(Nd)+s(Pr)+s(Dy));d=3 at. %−[81, 99.9] at. %*s(Co); e=0.3 at. %−[81, 99.9] at. %*s(Cu);and f=77 at. %−[81, 99.9] at. %*(s(Fe)+s(Co)).
 25. The method of claim 1wherein demagnetizing the magnetic material from the waste magnetassembly by cyclic heating and cooling of the magnetic materialcomprises demagnetizing a waste magnet part, that comprises the magneticmaterial, from the waste magnet assembly to fragment the adhesives thatbond the waste magnet part to a non-magnet part and to crack at leastone coating layer selected from: an electrolytic black Epoxy, a Ni, aNi—Cu, a Ni—Ni, a Ni—Cu—Ni, or a Zn coating layer of the waste magnetpart.
 26. The method of claim 25 wherein the cyclic heating and coolingcomprises: heating the magnetic material to a Curie temperature of therare earth material R; and cooling, after heating to the Curietemperature of the rare earth material R, the magnetic material at arate of at least 100° C./sec.
 27. The method of claim 1, whereinsintering and magnetizing the homogenous powder to form the recycledNd—Fe—B magnetic product that comprises 1.98 at. % oxygen or lesscomprises sintering and magnetizing the homogenous powder to form therecycled Nd—Fe—B magnetic product that comprises between 1.32 to 1.98at. % oxygen.